Myths about Aquaculture

Today, I picked up a few grocery items at the supermarket (I should mention I took notice of the Tilapia filets in the freezer section while shopping, which was a first), but when checking out, the issue arose I was back in college. I've known Pat for around 20 years, and she asks, "You're back in college?" "Yes," I replied, "I'm going there for Aquaculture." "Did you say Agriculture?," with a little bit of confusion. I laughed a bit, "Aqua culture. It's a little like Agriculture, except you farm fish." "So, when you finish, you're going to build a fish farm?" To which I replied, "No, actually I'm hoping to go on to UNCW for the Marine Science program."

So far, I've personally acquainted a small number of people, who either simply do not know what Aquaculture is, or perpetuating spreading myths about it. For instance, one lady I spoke with, told of a young girl attending the Aquaculture program, who "spent so much time in the water, she became sick of it, and had to change her major." This, simply is not true. I was also advised to get a diving suit.

I chuckle, and wonder what will I will hear next.

Not a myth: Far more alarming are the facts of big fish being fished out, dead zones in the oceans and seas from fertilizer run offs ... coral reefs dying, rain forests being cut down, levels of mercury in nature and other pollutants seeping into the ground water (even toxins in discarded electronic devices seeping into the ground water, and leaky Super Fund sites that will cost billions to clean up), none of which is in dispute. (Edward T. Babinski warning of fish, in shortage).

The growing Aquaculture industry may provide a sound mean to feed the world in the near future, without posing a threat to the environment.

Here's some information from the web, on further Aquaculture myths (which incidentally, seem to coincide with the warnings Dr. Holland has given our class at BCC) .. concerning the realities of success in Aquaculture. I will highlight those points:
In the course of working with hundreds of people interested in starting aquaculture enterprises, the author has arrived at two pieces of advice that he would like to pass along to you now:
1. Imitation, not innovation, is the key to success for beginning aquaculturists. A proven species and type of production facility is almost always the best choice. Few new fish farmers can afford the time or money needed for experimental systems.
2. Start small and learn as you grow. No matter how well you plan your aquaculture enterprise, you will learn a great deal during your first few years of operation. Starting small will allow you the flexibility to improve your facilities and time to develop your markets while minimizing your risk.

Some common myths about aquaculture

Fiction: Any fish or aquatic animal can be economically raised on a fish farm.
Fact: Most cannot be. Lack of control over reproduction and nutrition, make the farming of many desirable species impractical at present.

Fiction: I can find a site for a fish farm on my property.
Fact: Most sites are unsuited for fish farming because they lack adequate water or proper soils for pond construction.

Fiction: Fish farming is relatively easy.
Fact: Fish farming is agriculture and requires close management, hard work and the ability to tolerate risk.

Fiction: Fish farming is very profitable.
Fact: As in other types of agriculture, the level of profit is seldom excessive.

Fiction: Fish farming is a good retirement activity.
Fact: Runnning a fish farm requires hard physical work and can be stressful.

Fiction: Fishing is a good background for getting into fish farming.
Fact: Farming is the best background for getting into fish farming. Basic farming skills like operating a tractor, equipment repair, and welding are needed.
From: Getting Started in Aquaculture

Myth #1: Farmed salmon is not safe to eat.

Reality: Eating farmed salmon does not pose a health risk. Claims that eating farmed salmon can cause health risks such as cancer can unnecessarily frighten people and prevent them from enjoying the benefits of eating fish. Fish and seafood are an important part of a healthy and balanced diet.

Scientific studies indicate that trace amounts of PCBs (polychlorinated biphenyls) in both farmed and wild salmon are well within acceptable limits and similar to the amounts found throughout our food supply – in beef, chicken, pork and dairy products. PCBs and other contaminants are a legacy of industrial practices that find their way into the food chain in nearly all foods.

Health Canada and the Canadian Food Inspection Agency (CFIA) work together to ensure that our food supply is safe. For example, the CFIA conducts rigorous inspections of fish processing establishments across Canada and they analyze food samples for impurities, drug residues or disease-causing agents. Health Canada sets standards and policies for the safety of food and veterinary drugs sold in Canada.

Myth #2: Farmed salmon is not as nutritious as wild salmon.
Myth #3: No one is supervising salmon farms.
Myth #4: Salmon farms are bad for the environment.
Myth #5: Left-over food and feces from salmon farms pollutes the ocean.
Myth #6: Farmed salmon are pumped full of hormones and antibiotics.

Reality: Farmed salmon are not fed or injected with growth hormones. Antibiotics, if they are required, are provided by veterinarians. Health Canada has clear rules about drug use on food animals. Maximum residue limits for each drug are set and must be met through appropriate withdrawal times following treatment before the fish can be harvested. The CFIA monitors fish at federal processing plants to ensure they do not exceed the levels set by Health Canada.

When compared to land-based farmed animal production, salmon farming uses the least amount of antibiotics. In recent years, advances in vaccine development, similar to the practice used for raising livestock, have resulted in a significant reduction of antibiotic use.

Myth #7: Farmed salmon are full of additives to make it look like wild fish.
Myth #8: Escaped, farmed salmon are killing wild salmon stocks.
Myth #9: Escaped Atlantic salmon have been mating with wild Pacific stocks.
Myth #10: Farmed salmon spread disease to wild salmon.
Myth #11: Sea lice from farmed salmon are destroying pink salmon stocks in BC.
Myth #12: Food fish are being taken away from wild stocks to feed farmed fish.
Myth #13: The Science on the aquaculture issue seems confusing.
Myth #14: DFO supports the development of "Frankenfish".
Myth #15: Only closed-containment or land-based systems should be used to farm salmon.
Myth #16: Salmon farming is a small-scale experiment and has no future in helping ensure a global source of protein or local jobs.
From Myths and Realities about Salmon Farming

Aquaculture has now become a significant competitor for space in coastal and freshwater areas. To be accepted, however, it must demonstrate convincingly that aquaculture will not jeopardize other legitimate uses of the coastal, brackish and freshwater zones through causing unacceptable changes to the environment. As the aquaculturists are among the first to suffer the consequences of environmental deterioration their concern for the environment should, of necessity, be equal to or greater than that of those wishing to preserve it for other reasons. It has been pointed out that there are many "truths and myths" concerning aquaculture and the environment. Selected examples will be used to show how particular environmental factors are involved and what have been the results, probable consequences or misconceptions. The conclusions and ultimate message is clear; aquaculture can be practised successfully and profitably without compromising the environment. For this result to be achieved, however, it is necessary for aquaculture to employ only sound farming practices which penalize neither the aquaculturist nor the environment.
From Aquaculture Canada 2000 Abstracts

Other Myths
Are you one of those people who believe that farmed fish are full of medicines, and that they are really a sort of second-class food? If so, you are quite wrong, and have been for many years. Now, scientists at the Institute of Marine Research want to put paid to some long-standing myths about conditions in Norwegian aquaculture.
by Ingrid Dreyer
Fish are healthy food, and fish farming involve good exploitation of resources in comparison with meat production in agriculture. Fish are also an extremely popular product in many parts of the world. However, many people have a negative impression about the quality of farmed fish.
“In blind tests in which people taste fish food, most people prefer farmed fish to wild fish. However, if they are told that what they are tasting is farmed fish, their opinion of its quality automatically falls”, says research director Ole J. Torrissen of the Institute of Marine Research. He has no doubt that such attitudes are a holdover from the early days of fish-farming in the eighties, when consumption of medicines was high, and environmental problems around fish farms were common. But even though several decades of research and development and the establishment of solid monitoring and management systems have got rid of most of the childhood problems of fish farming, the negative attitudes still persist.
Antibiotics scarcely used now
One of the most enduring myths is that farmed fish are full of medicines.
“Many people believe that Norwegian fish farming still uses high doses of antibiotics. But this is far from being true. Nowadays, fish farming is virtually free of antibiotics, while significant quantities of antibiotics are fed to cattle, pigs, dogs and cats in Norway”, says Oivind Bergh, leader of the Institute’s Fish Health and Disease research group.
“More antibiotics are used to treat mastitis in cattle - a very common disease in agriculture - than are fed to all Norwegian fish”, says Bergh.
According to the Norwegian Food Safety Authority, 5.75 tonnes of antibiotics were used in this country in 2000, 4.9 tonnes of which were administered to farm livestock and domestic pets. At the same time, the number of organisms in Norwegian aquaculture is much greater than the number of animals in agriculture. There are around 600 million farmed fish, as against somewhat fewer than 40 million chickens and a million each of sheep, pigs and cattle. Prescriptions of antibiotics for the medical treatment of 4.5 million Norwegians come to between eight and ten times as much as the total amount fed to animals.
All the same, Bergh does not attempt to hide the fact that the introduction of new farmed species creates new challenges.
“The scallop farming industry had problems for a long time, but in the course of the past few years, new methods of cultivation have completely eliminated the use of antibiotics in this species as well. However, a certain increase in the use of antibiotics in cod farming has been observed. If this is to become a major industry, new methods will have to be developed to put a stop to this trend”, says Bergh, who points out that disease-free farmed species have not emerged without cost, and that major resources still need to be put into implementing control measures for all species.
Environmental toxins in farmed fish?
This spring, an article in the journal Science about environmental toxins in farmed fish aroused great deal of international attention. The article claimed that farmed salmon contain such high levels of toxins that it was inadvisable to eat farmed salmon more than once a month.
“The authors based this conclusion on the controversial model that they used for their assessment of health risk”, says seafood researcher Marc Berntssen at Norway’s National Institute for Nutritional and Seafood Research (NIFES). According to internationally recognised risk models (WHO and the EU) it is quite safe to eat salmon several times a month.
“Farmed salmon contain important nutrients, and the problem is largely that we do not eat enough fatty fish. Like the food authorities in other countries, NIFES recommends eating at least two portions of fish a week, one of which can well be fatty fish such as salmon”, says Berntssen.
From Putting Paid to myths about farmed fish, Institute of Marine Research

Myths and Legends of Aquaculture exploded!
It is important that Irish consumers are told the truth about the food that they eat. All too often though, they are misled by glib phrases and sound bytes that make for exciting journalism but do not give the true facts.
Aquaculture products in general and farmed Atlantic salmon in particular have been the subject of more than their fair share of this sort of sensationalist treatment.

To set the record straight BIM have provided the follow articles as a service to Irish fish consumers. The articles tell the consumer what they need to know so that they can make healthy eating choices for themselves and their families. Further Articles will be added through out 2007.

Aquaculture Myth Busters
Myth one: “Farmed Salmon is full of dyes!”

Myth two: "Fish in salmon farms are kept in the equivalent of a bathtub full of water"
From Myths and Legends of Aquaculture

Fish Food, Books, Aquaculture and more!
Many myths and fallacies concerning nutrition and feeding of fish are often regurgitated over and over again until it "almost" becomes a fact.

Aquaculture Links
Challenging the myths and misinformation surrounding Aquaculture.

More Stories on Google
Read More »

Largemouth Bass, Bluegill and Other Sunfishes

Notes from Fundamentals of Aquaculture, James W. Avault, Jr., Ph.D., pgs. 84-85

Carnivorous largemouth bass is farmed commercially in Taiwan on a limited scale, this species is mainly sought for sport in areas it occurs naturally, or has been introduced. Largemouth bass has wide distribution range, from Southern Canada, the Great Lakes, south into Mexico, and on the Atlantic Coast from Virginia to Florida. The Florida strain is sought after because it grows faster and reaches a large size, making it a trophy fish. Because of its popularity, State and national hatcheries have propagated the largemouth bass for decades. Fingerlings have been stocked into public waters and distributed to citizens for private ponds.

The bluegill (Lepomis macrochirus) has been produced in state and national hatcheries in combination with largemouth bass. In new sportfishing ponds that are fertilized, bluegill fingerlings are stocked in the fall at 3707/hectare (1500/acre). The following spring, largemouth bass are stocked at rate of 247 fingerlings per hectare (100 acres).

With most species, when a culture species is grown for food it is not desirable to reproduce in grow-out ponds. But in largemouth bass-bluegill ponds, the pond may never be drained as long as the fishing remains productive. The pond owner would naturally want both species to spawn naturally. Bluegill are prolific and usually spawn the first summer after stocking, and may spawn up to three or four times, depending on water temperature (above 27 degreesºC (80ºF).

Bass spawn once annually, in the spring when water temperature reaches 21ºC or 70ºF. The largemouth bass depend on the bluegill for a source of food, to realize maximum growth potential. Thinned down, bluegill have ample food supply and also reach a desirable size for sportfishing. Both species expand, filling the pond to its maximum carrying capacity and fish population ultimately reaches a "balance".

This balance is determined by three causes
1. Both species must reproduce each year.
2. Good fishing must exist. Though it may vary, generally the pond should allow harvesting up to 56 kg/ha (50 lb/ac) of largemouth bass and 225 kg/ha (200 lb/ac) of bluegill.
3. The population of forage (F) species (bluegill) must be in a proper ratio by weight in contrast with the carnivore (C) (largemouth bass), determining that a pond ratio F/C ratio may range from 1.4 to 10.

A number of other sunfishes are popular for sportfishing. The red-ear (Lepomis microlophus) has been stocked into largemouth bass ponds, to add variety to fishing. It grows slightly larger than bluegills, but is not prolific enough to be stocked alone with largemouth bass. Both white crappie and black crappie (Pomoxis annularis and P. nigromaculatus) are both sport-fish that grow well in large reservoirs, more than 20 ha (50 acres), with largemouth bass, bluegill and red-ear. Crappie compete with these species for food and space, and all species may become stunted in smaller farm ponds.

Entrepreneurs who are considering propagating largemouth bass and sunfish for commercial purposes must take into account the existing competition with state and national hatcheries. Some states prohibit farming of sportfish for commercial food purposes. However, there are limited possibilities for private investors, probably the best being operations of fee-fishing managed lakes, which appeal to urban citizens. Fishing rights can be leased by the day or annually, or charging by weight of fish which are caught.
Read More »

Largemouth Bass Culture

Largemouth Bass, Micropterus salmoides

Largemouth bass are freshwater bass which belong to the family Centrarchidae.

Two subspecies:
1. Northern strain
2. Florida strain (
Scientists and anglers had already recognized by 1932 that largemouth bass in peninsular Florida grew to a larger size and had different coloration than their northern counterparts. These differences, as well as other physical characteristics, were used to classify Florida largemouth bass as a distinct subspecies in 1949. Although each is recognized as a unique biological unit, the two subspecies (Florida bass [Micropterus salmoides floridanus] and northern bass [Micropterus salmoides salmoides]) freely interbreed. Florida bass have been widely introduced throughout the nation because of their potential for producing trophy-size fish. However, native populations of this subspecies are unique only to the central and southern portions of the Florida peninsula. As a result, they represent a natural resource that is both biologically unique and economically valuable.(Black Bass Genetics in Florida)

Closely related species that are cultured:
1. Smallmouth bass (M. dolomieui)

2. Spotted bass (M. punctulatus)
(Texas State)

Largemouth bass live in warm, slow moving waters around rich vegetative soft bottoms. Smallmouth bass are a related game species found in faster, cooler water that may require less vegetative cover. Largemouth bass, Smallmouth bass and Spotted bass are known collectively as the Black bass.

Intensive Largemouth Bass Culture Commercial Production
North Carolina is one of the few states which permit commercial culture of bass. It is the only state on the East Coast that specifically permits licensed fish farmers to culture food-size Largemouth bass.

The Largemouth bass market is small. Currently live sales go to Asian-Americans in the northeastern US. Live haulers pick up live largemouth bass at the farm, and may pay up to $6 per lb, in cash. These fish must be at least 1.5 lbs, excellent physical condition and disease-free to bring this price. High price and ready market has resulted in recent interest in intensive commercial production of largemouth bass.

Dr. James Tidwell and others at Kentucky State University conducted research which demonstrate largemouth bass can be stocked at high rates, up to 5,000 per acre. Fed a high-protein pelleted feed, and grown to market size in a reasonable period of time (from 6” fingerlings to 1.5 lb fish in 12-18 months).
(Kentucky State University)

Problems with intensive production of Largemouth bass:
1. Cannibalism (well graded fish at stocking, additional grading may be required before fish are finished out).
2. Bird predation Compared with other species, birds are one of the greatest predators.
3. Unknown nutritional requirements.
4. No approved disease treatments.
5. Other problems yet to be determined (Very little intensive culture experience to go on at this point). (

Bass-Bream Culture in Farm Ponds
Farm ponds are most often hill ponds (also known as watershed ponds [Watershed or embankment ponds, are formed by constructing a dam to collect stream or surface runoff] NC State Fisheries). Excavated ponds are also sometimes constructed in low areas in the coastal plain for the same purpose.

Most farm ponds are located in the upper coastal plain and the piedmont in NC. They are used for many and varied purposes on farms throughout the U.S.A., including:
1. Irrigation
2. Livestock watering
3. Flood control
4. Erosion control

For reasons #3 and #4 above, many of these ponds have been constructed with large (up to 75% of cost) subsidies from the Soil Conservation Service since the 1930’s. More than 100,000 have been constructed in NC alone (NC has 60,000 farms, and most have at least 1 farm pond on the property).

Farm ponds once served another important function on farms in the Southeastern US: Production of fish as food for the farm family.

Homer Swingle (Auburn University, Alabama) conducted extensive research on the use of farm ponds as a source of high-quality fish protein for farmers in the South, beginning in the 1930’s. Swingle’s work laid the foundation for further research on farm-pond fish culture that continues to the present day.

Many states provide largemouth bass and bream fingerlings free of charge to farmers for farm-pond stocking. Many states, including North Carolina have discontinued this practice.

Largemouth bass and bream of various species are produced by private hatcheries for sale to individuals for private lake or ponds. It is a lucrative business, and there are several suppliers of Largemouth bass, bluegill, red-ear, hybrid bluegill, etc. in NC, including graduates of the BCC aquaculture program. (Southeast Pond Stocking of Pender County, specializes in largemouth bass, bluegill, shellcracker, channel catfish, grass carp, hybrid striped bass, koi, fathead minnows, hybrid bluegill, tilapia, black crappie, F1 hybrid largemouth bass) (NC State Agriculture) Currently only 3-4 active gamefish hatcheries exist in North Carolina and Southeast Pond Stocking, is run by BCC graduates Kevin Patterson and Rick Stuckman.

Most suppliers purchase fingerlings from private hatcheries and provide stocking services for private pond and lake owners. (A list of services,

Largemouth bass become carnivorous when they become adults, and having a preference for smaller fish, so ponds and lakes must be stocked with a suitable forage species to support Largemouth bass populations.

Debate continues over
1. Largemouth bass stocking rate.
2. Forage species stocking rate.
3. The best forage species to use.

Commercially, the most common forage species for Largemouth bass is the Bluegill (Lepomis macrochirus).
Bluegill image based on Michigan Science Art

Recommended stocking in North Carolina:

Unfertilized ponds:
a. 350/acre 1-2” bluegill stocked in Oct-Nov
b. 150/acre 1-2” red-ear sunfish stocked in Oct-Nov
c. (optional) 50/acre 2-4” channel catfish stocked in Oct-Nov
d. 50/acre 2-4” LMB stocked the following June

Fertilized (or fed) ponds:
a. 700/acre 1-2” bluegill stocked in Oct-Nov
b. 300/acre 1-2” red-ear sunfish stocked in Oct-Nov
c. (optional) 50/acre 2-4” channel catfish stocked in Oct-Nov
d. 100/acre 2-4” LMB stocked the following June

Many people avoid stocking catfish because catfish may upset the bass-bream “balance”. Some scientific evidence exists for this.

The preferred stocking strategy for ponds and small lakes (described above) in NC is because,

1. Bluegill and red-ear have traditionally shown to be an excellent forage species for bass.

2. Bluegill itself is an excellent foodfish for people. Some people prefer bluegill over bass.

3. Largemouth bass do a good job of keeping sunfish populations in check, preventing overpopulation and stunting.

The greatest problem in Largemouth bass/sunfish ponds is overfishing of bass, and/or underfishing sunfish, resulting in overpopulating the pond with sunfish. The sunfish then may become stunted, too small to be eaten by people, while bass population is reduced in number and larger, which are seldom caught by anglers.

To maintain the pond's “balance” a farm pond should be harvested on a regular schedule by angling :

Depending on productivity:

1. 10-40 lbs/acre of bass should be harvested each year.
2. 40-160 lbs/acre of sunfish should be harvested each year.

Use the lowest figures for unfertilized ponds constructed in soils of low fertility. Use the highest figures only for well-managed fertilized ponds built on highly productive agricultural land, or fed ponds. If a pond owner can’t eat 160 lbs of bream from his pond each year, give them away or bury them!

Stocking alternative forage species:

1. Red-ear sunfish (Lepomis microlophus) – has a lower reproductive rate than bluegill, so may be less likely to overpopulate or become “stunted”.

Red-ear Sunfish
Red-ear sunfish (Lepomis microlophus), an alternative forage species for Largemouth bass.
Red-ear sunfish image based on Texas Parks and Wildlife

2. A 70:30 mix of bluegill and red-ear (as recommended by NC Cooperative Extension).

3. Hybrid bluegill – usually a cross between male bluegill and female green sunfish. Very popular with pond and lake owners, but not recommended, because:

a. Hybrids are 90% male, have a very low reproductive rate, and may not provide adequate forage for the bass.

b. The hybrids back-cross and revert back to a fish that most resembles green sunfish after 1-2 generations. Green sunfish rapidly overpopulate the pond and become stunted, useless as a foodfish for people.

Many other stocking and management strategies in other states and other regions of the US, depending on:

1. Climate
2. Soil fertility
3. Watershed chartacteristics
4. Other environmental factors.

Each state has developed its own recreational fishing pond management strategies and recommendations. Consult your local Cooperative Extension office for recommendations in your area.

References: Largemouth Bass, Texas State Parks and Wildlife

Notes from BCC with modifications and additions, January 28, 2006
Read More »

Largemouth Bass, Micropterus salmoides

Largemouth Bass, Micropterus salmoides

Largemouth Bass
Image based on (Texas State Wildlife)

Physical Description and Taxonomy
Micropterus, from the Greek, "small fin" salmoides, from the Latin, salmo, "trout"; hence "trout-like" Common name from large mouth, the line of which extends back past the eye. Other common names include: Bigmouth Bass, Bigmouth Trout, Black Bass, Bucketmouth Bass, Green Bass, Green Trout, Hawg, Hog, Lineside, Lake Bass, Openmouth Bass, Oswego Bass, Slough Bass, Welshman

Kingdom Animalia
Phylum Chordata, animals with a spinal chord
Subphylum Vertebrata, animals with a backbone
Superclass Osteichthyes, bony fishes
Class Actinopterygii, ray-finned and spiny rayed fishes
Subclass Neopterygii
Infraclass Teleostei
Superorder Acanthopterygii,
Order Perciformes, perch-like fishes
Suborder Percoidei
Family Centrarchidae, sunfish
Genus Micropterus, black bass, largemouth bass (

Largemouth bass grow 4 to 6 inches (10 to 15 cm) during their first year, 8 to 12 inches (20 to 30 cm) in two years, 16 inches (40 cm) in three years. They are usually green with dark blotches that form a horizontal stripe along the middle of the fish on either side. The underside ranges in color from light green to almost white. They have a nearly divided dorsal fin with the anterior portion containing nine spines and the posterior portion containing 12 to 13 soft rays. Their upper jaw reaches far beyond the rear margin of the eye. (Texas State Parks and Wildlife)
Micropterus salmoides has a large mouth, a notch between the two dorsal fins, and a dark stripe along the side of the body (Bailey et al., 2004). This black band is seemingly made up of small oval shapes to a closer eye. Coloration is variable, but is usually a darkish green on the back and sides, fading to an off-white on the belly. The anterior dorsal fin has nine to eleven spines while the posterior dorsal fin has twelve to fourteen rays (Boschung et al., 2004). The average weight of M. salmoides is one kilogram; however, certain individuals have reached weights of over ten kilograms. Males usually do not surpass 40 cm, while females can reach up to 56 cm in length. (Bailey, Latta, and Smith, 2004; Boschung, Mayden, and Tomelleri, 2004) (University of Michigan)

Largemouth bass were originally distributed throughout most of what is now the United States east of the Rockies, including many rivers and lakes in Texas, with limited populations in southeastern Canada and northeastern Mexico. Because of its importance as a game fish, the species has been introduced into many other areas worldwide, including nearly all of Mexico and south into Central and South America. Largemouth bass seek protective cover such as logs, rock ledges, vegetation, and man-made structures. They prefer clear quiet water, but will survive quite well in a variety of habitats. (Texas State Parks and Wildlife)
Micropterus salmoides is native to eastern North America and historically ranged from southern Canada to northern Mexico, and from the Atlantic coast to the central region of the United States. Since the beginning of the twentieth century largemouth bass have been introduced successfully all over the world. (Carlander, 1977; Hubbs, 1964; Page and Burr, 1991) Largemouth bass prefer quiet, clear waters with abundant vegetation (Iguchi and Matsuura, 2004). More specifically, they prefer shallow water that is usually no deeper than 2.5 meters, but they sometimes occupy deeper regions. Abundant vegetation is important because it allows bass to hide from their prey and provides protection against predators.
Several countries report adverse ecological impact after introduction.(University of Michigan and

Temperature Requirements
Growing: 55-80 F / 10 – 32°C; 47°N - 26°N (
Spawning: 60-65 F (

Fry feed primarily on zooplankton, aquatic insects and insect larvae. At about two inches in length they become active predators. Adults feed almost exclusively on other fish and large invertebrates such as crayfish and frogs. Larger fish prey upon smaller bass. Sunfish are the food of choice for most adult largemouth bass. Sometimes cannibalistic. (Olsen and Young, 2003, Texas State Parks and Wildlife, University of Michigan,

Commercial Production
The production, rearing and stocking of largemouth bass (Micropterus salmoides) represents a large economic asset in the aquaculture industry of the midwestern U.S., requiring extensive information on the biology of this species.
( Comparison of Experimental Growth Rates of Pond-Raised Largemouth Bass, Micropterus salmoides, Fed Natural and Artificial Foods)
Size: 1.0 - 2.5 lbs for food and 4-8 inches for fingerlings
Feed requirements: Protein: 40% diets are normally fed from fingerlings to adults after fingerlings have been trained to accept commercial diets.
Fat: 8-10%. Ponds for spawning and grow-out to food fish size. Small fingerlings are normally removed from ponds and trained to accept commercial diets using flow through systems. (

Spawning Requirements
In Texas spawning begins in the spring when water temperatures reach about 60°F. This could occur as early as February or as late as May, depending one where one is in the state. Males build the nests in two to eight feet of water. Largemouth bass prefer to nest in quieter, more vegetated water than other black bass, but will use any substrate besides soft mud, including submerged logs. As in Guadalupe bass, once the female has laid eggs in the nest (2,000 to 43,000) she is chased away by the male who then guards the precious eggs. The young, called fry, hatch in five to ten days. Fry remain in a group or "school" near the nest and under the male's watch for several days after hatching. Their lifespan is on average 16 years. (Texas State Parks and Wildlife)

Natural Enemies
Larval and juvenile largemouth bass are prey species of yellow perch, walleye, northern pike, and muskellunge. As adults, largemouth bass can usually escape most predators. The primary predators on adult largemouth bass are humans. (Paulson and Hatch, 2002) Preyed upon by herons, bitterns, and kingfishers (Ref. 1998). Excellent food fish (Ref. 1998). (University of Michigan and

References: Largemouth Bass
Read More »

Which Fish Do Fast Food Restaurants Use?

McDonalds' Fish Filet Sandwich
The Filet-O-Fish is a fish sandwich sold by McDonald's since 1963. It contains a breaded fish patty made from Pollock or Hoki.
Source, 1 and 2

Alaska pollock is commonly used in the fast food industry, for example the fish filet at both McDonald's and Burger King are also made from Alaska pollock.
The Alaskan pollock is said to be "the largest remaining source of palatable fish in the world." Atlantic pollock is largely considered to be a white fish, although it is a fairly strongly flavored one. Alaska pollock has a much milder taste, whiter color and lower oil content. (Pollock, Wikipedia)

Read More »

Rainbow Trout, Salmo gairdneri

Rainbow Trout, Salmo gairdneri (=Oncorhynchus mykiss)
(Salmon Trout, Steelhead Trout, or Coastal Rainbow Trout)

Rainbow Trout

Physical Description and Taxonomy
Class: Osteichthyes
Order: Salmoniformes
Family: Salmonidae
Genus: Oncorhynchus
Species: mykiss
In 1992 the steelhead trout, Salmo gairdneri (the species named in memory of Meredith Gairdner, a 19th-century naturalist) was reclassified in the genus Oncorhynchus ("hooked nose"), and mykiss (a Siberian word for the species). There are two races, both native to Western North America. The common name of the freshwater O.m. is rainbow trout, a colorful game fish that has been transplanted worldwide. The sea-run, or anadromous rainbow trout is called steelhead, a word that entered the common nomenclature in the early 1880s.
Unlike salmon, steelhead can spawn several times, although the hydropower dams on the Columbia River system have interfered with that pattern, and the species has been classed as threatened under the Endangered Species Act. On December 12, 2000, biologists for the Yakama Indian Nation released the first of 110 revived and rehabilitated kelts—as between-spawning steelhead are called—into the Yakama and Columbia Rivers. All were wearing identification tags, clipped fins, and inch-long cylindrical radio transmitters in their throats, for tracking, DNA testing, and genetic research. Record-class steelhead can attain a length of up to 45 inches, and a weight of more than 40 pounds. (
In 1989 both the genus name and specific name of the rainbow trout were changed (see Smith and Stearley 1989). Thousands of publications cite Salmo gairdneri as the name of the rainbow trout; now we call it Oncorhynchus mykiss. The genus name was changed from Salmo to Oncorhynchus partly based on fossil evidence because the Pacific trouts were thought to be more closely related to the Pacific salmon than to the Atlantic salmon [the name carrier or type of Salmo]. Pacific trout and salmon are now classified as Oncorhynchus. The species name gairdneri was changed to mykiss when it was thought that mykiss from Kamchatka, Russia, was the same as gairdneri; since mykiss was described first, that name had priority for use over gairdneri. (

Native Range/Habitat
Steelhead is a name given to rainbow trout which live in the Great lakes. Rainbow trout are native to the Pacific Ocean along North America and to rivers and other fresh waters of North America west of the Rocky Mountains. They are a popular game fish, and for this reason have been introduced all over the United States.

Temperature Requirements
Great lakes steelhead are usually found in waters less than 35 feet deep at temperatures of 58-62 degrees F. They are often found near stream outlets, especially in spring and early summer.

In the lake-dwelling part of their life cycle, they wander along the shoals eating plankton, minnows, surface and bottom insects and other aquatic life. Although they feed primarily in mid-depths, they do take surface insects, including fly fishermen's flies. Larger rainbows will eat other small fish if available.

Commercial Production
Steelhead are valiant fighters and their flesh is outstanding no matter how it is cooked. An unbeatable combination that makes them one of the most popular North American sport fish. (
The production of rainbow trout has grown exponentially since the 1950s, especially in Europe and more recently in Chile. This is primarily due to increased inland production in countries such as France, Italy, Denmark, Germany and Spain to supply the domestic markets, and mariculture in cages in Norway and Chile for the export market. Chile is currently the largest producer. Other major producing countries include Norway, France, Italy, Spain, Denmark, USA, Germany, Iran and the UK.
There are many outputs from rainbow trout culture, which include food products sold in supermarkets and other retail outlets, live fish for the restocking of rivers and lakes for recreational put-and-take game fisheries (especially in the USA, Europe and Japan), and products from hatcheries whose eggs and juveniles are sold to other farms.
Products for human consumption come as fresh, smoked, whole, filleted, canned, and frozen trout that are eaten steamed, fried, broiled, boiled, or micro-waved and baked. Trout processing wastes can be used for fish meal production or as fertiliser. The fresh fish market is large because the flesh is soft and delicate, white to pink in colour with a mild flavour. Food market fish size can be reached in 9 months but 'pan-sized' fish, generally 280-400 g, are harvested after 12-18 months. However, optimal harvest size varies globally: in the USA trout are harvested at 450-600 g; in Europe at 1-2 kg; in Canada, Chile, Norway, Sweden and Finland at 3-5 kg (from marine cages). Preferences in meat colour also vary globally with USA preferring white meat, but Europe and other parts of the world preferring pink meat generated from pigment supplements in aquafeed.
Strict guidelines are in place for the regulation of rainbow trout for consumption with respect to food safety. Hygiene and safe transportation of fresh fish are of paramount importance, to ensure that fish are uncontaminated by bacteria, in accordance with food agency directives.
Status and trends
The rainbow trout farming industry has been developing for several hundred years, and many aspects are highly efficient, using well-established systems. However, current research and development is continually attempting to increase production efficiency and sales by increasing rearing densities, improving recirculation technology, developing genetically superior strains of fish for improved growth, controlling maturation and gender, improving diets, reducing phosphorous concentrations of effluents, and developing better marketing. One method that has been developed is a genetically modified hormone that is effective in reducing production costs. However, problems may lie ahead as public opinion towards genetically-modified products continues to be negative. As production continues to rise research is needed to keep costs to a minimum so the industry can move forward. (FAO.ORG)

Spawning Requirements
Great Lakes steelhead enter their spawning streams from late October to early May. At the present most spawning occurs in the spring, although more steelhead are beginning to spawn in fall. Spawning takes place in a bed of fine gravel, usually in a riffle above a pool. Steelhead don't necessarily die after this; they may live to reproduce for as many as five successive years. Most rainbow trout return home to spawn in the stream in which they were born or planted.
Trout eggs hatch in four to seven weeks, depending on water temperature. Young trout may travel downstream to the lake in their first summer, or they may remain from one to three years in their home stream before migrating lakeward.
Individual growth varies greatly even within the same population. Most Great lakes steelhead reach sexual maturity at age three to five years, ahead of females. A mature 16-inch fish living in the Great lakes may continue to grow throughout its life and could reach 36 inches in length and up to 20 pounds in weight. However, average adult size for steelhead in 9 to 10 pounds while life expectancy in the Great Lakes is six to eight years.

Natural Enemies
Larger fish, fish-eating birds and mammals and sea lamprey are the steelhead's natural enemies. In turn, the steelhead finds itself competing with other salmon and trout, other predatory fishes and a variety of bottom feeders, for its food. It also competes with salmon and trout for spawning grounds. (
There are a variety of diseases and parasites that can affect rainbow trout in aquaculture, which are summarised here. Prevention is the most important measure; good hatchery sanitation by restricting access, installing disinfectant footbaths and disinfecting equipment reduces the exposure of vulnerable fish to disease-causing agents.
In some cases antibiotics and other pharmaceuticals have been used in treatment but their inclusion in this table does not imply an FAO recommendation. (Cultured Aquatic Species Information Programme, Oncorhynchus mykiss)

Steelhead, Oncorhynchus mykiss,
Read More »

Brook Trout, Salvelinus fontinalis

Brook Trout Salvelinus fontinalis
(Speckled trout)

Brook Trout

Salvelinus fontinalis (Mitchill, 1814)
Taxonomy and Nomenclature
Taxonomic Hierarchy
Kingdom Animalia -- Animal, animals, animaux
Phylum Chordata -- chordates, cordado, cordés
Subphylum Vertebrata -- vertebrado, vertebrates, vertébrés
Superclass Osteichthyes -- bony fishes, osteíceto, peixe ósseo, poissons osseux
Class Actinopterygii -- poisson épineux, poissons à nageoires rayonnées, ray-finned fishes, spiny rayed fishes
Subclass Neopterygii -- neopterygians
Infraclass Teleostei
Superorder Protacanthopterygii
Order Salmoniformes -- salmons, saumons
Family Salmonidae -- salmonids, salmons, trouts, trouts and salmons, truchas y salmones, truites et saumons
Subfamily Salmoninae
Genus Salvelinus Richardson, 1836 -- chars
Species Salvelinus fontinalis (Mitchill, 1814) -- brook trout, charr, omble de fontaine, salter, sea trout, trucha de arroyo

Taxonomic Rank: Species
Synonym(s): Common Name(s): brook trout [English]
charr [English]
omble de fontaine [French]
salter [English]
sea trout [English]
trucha de arroyo [Spanish] (

Physical Description
The brook trout's body is elongate with an average length of 38.1-50.8 cm, is only slightly laterally compressed; the body has its greatest depth at or in front of the origin of the dorsal fin (Scott and Crossman, 1985). Another physical characteristic of the brook trout is an adipose fin and a caudal fin that is slightly forked (Hubbs and Lagler, 1949). Brook trout have 10-14 principle dorsal rays, 9-13 principle anal rays, 8-10 pelvic rays, and 11-14 pectoral rays (Scott and Crossman, 1985). The brook trout also has a large terminal mouth with breeding males developing a hook or kype on the front of the lower jaw (Scott and Crossman, 1985).
The coloration of the brook trout is very distinct and can be spectacular. The back of the brook trout is dark olive-green to dark brown, sometimes almost black, the sides are lighter and become silvery white ventrally (Scott and Crossman, 1985). On the back and top of the head there are wormy cream colored wavy lines known as vermiculations which break up into spots on the side (Scott and Crossman, 1985). In addition to the pale spots on the side there are smaller more discrete red spots with bluish halos (Scott and Crossman 1985). The fins of the brook trout are also distinct; the dorsal fin has heavy black wavy lines, the caudal fin has black lines, the anal, pelvic and pectoral fins have white edges followed by black and then reddish coloration (Scott and Crossman, 1985). (Hubbs and Lagler, 1949; Scott and Crossman, 1985)Some key physical features: ectothermic ; heterothermic ; bilateral symmetry. (

Native Range and Habitat
Brook trout are found as far south as Georgia in the Appalachian mountain range and extend north all the way to Hudson Bay. From the east coast their native range extends westward to eastern Manitoba and the Great Lakes (Willers, 1991). The fish has been introduced, very successfully in some areas, into many parts of the world including western North America, South America, New Zealand, Asia, and many parts of Europe (
The brook trout is native to small streams, creeks, lakes, and spring ponds. Some brook trout are anadromous. Though commonly considered a trout, the brook trout is actually a char, along with lake trout, bull trout, Dolly Varden and the Arctic char. It is native to a wide area of eastern North America, including most of Canada from the Hudson Bay basin east, the Great Lakes–Saint Lawrence system, and the Mississippi River drainage in the United States as far south as northern Georgia. (Wikipedia)

Temperature Requirement
Brook trout require cool, clear, spring-fed streams and pools. They can be found under cover of rocks, logs, and undercut banks and have been described as stationary. Larger brook trout often inhabit deep pools moving to shallow water only to feed. They prefer temperatures from 57–60 degrees F. (

Brook trout have been described as voracious feeders with the potential to consume large numbers of zooplankton, crustaceans, worms, fish, terrestrial insects, and aquatic insects. Ephemeroptera, Trichoptera, and Diptera often make up a large component of their diet. However, they will often feed on whatever is most readily available.
Brook trout are avidly sought after by sport anglers, for food as well as for the sport. They can be caught by using various bait and lures including worms, crickets, grasshoppers, wet and dry flies, spoons, and spinners. (

Commercial Production
The potential for commercial production of brook trout Salvelinus fontinalis, however, is constrained by the lack of published protocols for producing the sex-reversed males required to create monosex female stocks. Immersion and immersion plus feeding treatments with 17α-methyltestosterone (MT) and 17α-methyldihydrotestosterone (MDHT) were applied to genotypically female gynogenetic brook trout to induce phenotypic sex reversal. The fry were exposed to a 6-h immersion in a solution of MT or MDHT on day 10 following completion of hatch and/or to a steroid-treated diet for 60 d beginning at first feeding. Immersion dosages were 0.5 or 1.0 mg/L, and feeding dosages were 1.0 or 2.0 mg/kg of feed for MT and 0.5 or 1.0 mg/kg for MDHT. Phenotypic sex of the fish was determined 19 or 22 months after first feeding. Control gynogenetic fish were 100% phenotypic females. Treatments with MT had minimal effect: most fish remained female, with only a low incidence of phenotypic males (1-3% in four of the treatments), intersex fish, or sterile fish. In contrast. a substantial number of phenotypic males were observed in several of the MDHT treatments, with the highest proportion (45%) occurring in the 0.5 mg/L immersion plus 0.5 mg/kg feeding treatment. Sperm was obtained from 29 males from five MDHT treatment groups and one MT treatment group examined at maturity (22 months) and was used in progeny tests of these males. The progeny were 100% female, confirming the male parents to be genotypically female. These protocols may be used to create sex-reversed brook trout males for the production of monosex female progeny, although additional trials are ongoing to test similar MDHT immersion dosages applied once or multiple times, with or without feeding treatments, to identify protocols with increased efficacy. (
The brook trout is very popular with anglers, particularly fly fishermen. Today, many anglers practice catch-and-release tactics to preserve remaining brook trout populations, and organizations such as Trout Unlimited have been in the forefront of efforts to institute air and water quality standards sufficient to protect the brook trout. Revenues derived from the sale of fishing licenses have been used to restore many sections of creeks and streams to brook trout habitat. Brook trout are also commercially raised in large numbers for food production, being sold for human consumption in both fresh and smoked forms. Because of its dependence on pure water and a variety of aquatic and insect life forms, the brook trout is also used for scientific experimentation in assessing the effects of pollution. (Wikipedia)

Spawning Requirements
Brook trout spawn in the fall within sand and gravel areas where upwelling groundwater occurs. Lake-dwelling fish spawn in tributary streams or along the shoreline. Spawning takes place from late September to November during daytime, by contrast with night-time spawning lake trout. As spawning season approaches the colors of brook trout are greatly intensified, especially in males whose flanks and belly become orange-red with a black stripe along each side. Aggregations of spawning brook trout can often be observed in small tributaries and along lake shorelines, with solitary females seen digging and remaining within the perimeter of shallow nests, and numerous males looking for an opportunity to dart into these nests to fertilize eggs deposited by the resident female. Brook trout "redds" or nests are often found in large aggregations.
Surviving brook trout eggs hatch from February to April, still buried within their gravel spawning beds. Young brook trout grow faster than lake trout because small brook trout are able to live in warmer nearshore and tributary areas that produce abundant insect larvae and other small crustaceans. Larger brook trout are able to feed upon small fish and crayfish, though these fish are also restricted to cold, deepwater habitats during warm mid-summer conditions. Although brook trout are relatively acid-tolerant and can withstand pH conditions as low as 5.0, many brook trout populations in the southwestern Adirondacks and Catskills have been eliminated or greatly reduced due to decades of acid rain deposition. Brook trout have also been eliminated from suitable coldwater habitats within lakes and streams due to predation and competition with non-native smallmouth bass and brown trout. (
Brook trout spawn in late summer or autumn depending on the latitude and temperature (Scott and Crossman, 1985). The type of area required for brook trout spawning is one that offers loose, clean gravel in shallow riffles or shoreline area with an excellent supply of upwelling, oxygen-rich water (LaConte, 1997). Mature fish have been known to travel many miles upstream to reach adequate spawning grounds (Scott and Crossman, 1985). Females are able to detect upwelling springs or other areas of ground-water flow, which make for excellent spawning grounds. Brook trout reach maturity on an average at the age of two and spawn every year, although their size at first maturity depends on growth rate and the productivity of thier habitat (Everhart, 1961). Males often outnumber females at the spawning site, but only rarely is more than one male able to fertilize the eggs in a particular redd (Scott and Crossman, 1985; Blanchfield et al., 2003). The females clear away debris and silt with rapid fanning of her caudal fin while on her side, creating a redd (Scott and Crossman, 1985). The redd is where the eggs will be deposited and fertilized after the males compete for spawning right to the female (Scott and Crossman, 1985). The redd actually resembles a pit that is 4-12 inches in depth (Everhart, 1961). To gain the spawning right of the female the males compete for position by nipping and displaying themselves to the competitor males (Mills, 1971). When spawning is actually taking place the male takes a position to hold the female against the bottom of the redd and both of the fish vibrate intensely while eggs and milt are simultaneously discharged (Scott and Crossman, 1985). Very shortly after this exchange takes place the female works to cover the fertilized eggs with gravel by digging slightly upstream and letting the current carry the gravel down to fill the redd (Everhart, 1961). The eggs are initially adhesive to prevent them from washing away so they are able to incubate within the gravel (Scott and Crossman, 1985). The total time of incubation depends on factors such as temperature and oxygen (Scott and Crossman, 1985). After hatch the fry remain in the gravel until the yolk sac is absorbed then the fry swim up out of the gravel to begin the next stage of their life (Scott and Crossman, 1985). (Blanchfield, Ridgway, and Wilson, 2003; Everhart, 1961; LaConte, 1997; Mills, 1971; Scott and Crossman, 1985 (
Read More »

Effects of High and Low pH Levels in Water on Fish

Effects of pH Levels on Aquatic organisms
Very high ( greater than 9.5) or very low (less than 4.5) pH values are unsuitable for most aquatic organisms. Young fish and immature stages of aquatic insects are extremely sensitive to pH levels below 5 and may die at these low pH values. High pH levels (9-14) can harm fish by denaturing cellular membranes.

Changes in pH can also affect aquatic life indirectly by altering other aspects of water chemistry. Low pH levels accelerate the release of metals from rocks or sediments in the stream. These metals can affect a fish’s metabolism and the fish’s ability to take water in through the gills, and can kill fish fry.

The term "pH" was originally derived from the French term "pouvoir hydrogène," in English, this means "hydrogen power." The term pH is always written with a lower case p and an upper case H. (

Testing pH
Student at BCC Aquaculture Center, testing pH levels in water.

High pH Levels Effect
At high pH (>9) most ammonium in water is converted to toxic ammonia (NH3), which can kill fish. Moreover, cyanobacterial toxins can also significantly influence fish populations. (

Testing pH
High pH level.

Testing pH
Water sample which indicate a high pH level when test, in this case could be adjusted by straining water through peat. The instructor at BCC compared it to "tea," which is dark, but safe for fish. Added to the aquarium, the pH level was brought down within a safe range.
Testing pH

All images, including Aquaculture Facility located here.

Fish kill at low pH in a Norwegian river
Zoological Laboratory, University of Bergen, 5000 Bergen, Norway.
THE decline in freshwater fish populations in parts of southern Norway is associated with increasing acidity in rivers and lakes1. The salmon has been eliminated from many rivers, and hundreds of lakes have lost their trout populations. The chief cause of increased acidity is acid precipitation which is the product of the emission, oxidation and long-distance transport of air pollutants, particularly sulphur dioxide2,3. Similar observations of acid rain and the disappearance of freshwater fish populations have been made in the United States, Canada and Sweden4−6. (

The Acid Test: Is Your Pond pH Too Low?
News from Texas A&M University, 3/24/2006, R. Burns
Winter months are an ideal time to adjust pH and alkalinity because the treatment, usually an application of agricultural lime, takes time to have an effect," Higginbotham said. "Depending upon weather conditions, the fineness of lime used and the method of application, the time delay may be from a few days to as much as a month."
Alkalinity relates to the "buffering capacity" of water, its capacity to reduce fluctuations in pH, he said.
Pond water pH becomes low – acidic – primarily because local soils are acidic. But not all soils are acidic; not all ponds need liming. The best way to know for certain is to have a simple water test done to determine both alkalinity and pH, Higginbotham said.
But generally, acid soils and consequently acid pond water are problems confined to East Texas.
"The further east of I-35 you go, and the further north of I-10, the higher the likelihood you need to lime your pond," he said. "Another way to determine if you might need to lime is if there's an agricultural liming service in your area. If not, then you probably don't need to lime your pond."
Water pH and alkalinity must be correct for pond fertility programs to work. In such a program, fertilizers containing nitrogen, phosphorus and potassium are added to encourage the growth of microscopic plants called phytoplankton. Microscopic animals called zooplankton feed on the phytoplankton, Higginbotham said.
And many forage fish, including bluegill, feed on the zooplankton. Game fish, such as largemouth bass, feed on the bluegill. The result of a properly managed fertility program is better fishing, and since the phytoplankton absorb wastes, better recreational use of the pond overall. Proper liming can improve phosphorus availability and enhance the health of the pond.
But even without a fertility program, liming can make the critical difference to fish health, particularly where soils are highly acidic such as East Texas, Higginbotham said. Low pH values are usually coupled with low alkalinity.
"Total alkalinity below 20 parts per million can result in large swings in daily pH values, which can stress fish," he said. "And a pH below 5.0 approaches the 'acid death point' for many fish species." (Continued... USDA)

Fish kills resulting from low pH (acidic water) are even less common than chemical kills. Usually pH kills occur when heavy rains wash tannin (an acidic substance found in leaves) from wooded areas. Low pH can be increased easily by applying agricultural limestone. The amount of lime required can be determined by sending samples of the mud from the pond bottom to the NCDA Soil Analysis Laboratory for analysis. (See the earlier section on liming procedures.) Contact your county Agricultural Extension Service office for assistance in sending soil samples. (NCSU)

pH Measurements
[(+/-) 1500 pixels
106 k] The pH of some aqueous solutions: Measurements of pH are usually made with a meter connected to a glass electrode immersed in the solution.

Low ph in Oceans (related to climate change from emmissions) and Carbonic Acid
Acid seas threaten to make British shellfish extinct
Sunday 12 March 2006, From Plymouth Marine Laboratory
SHELLFISH, crabs, lobsters and a host of other familiar species could become extinct around Britain and Europe because our seas are becoming steadily more acidic.
An official report is to warn that carbon dioxide generated by human activity, already linked to climate change, is also sharply altering the chemistry of the oceans. The gas forms carbonic acid when it dissolves into sea water.
Some species, such as corals and certain plankton, are so sensitive to the rising acidity that they could be in rapid decline within decades. Others, such as crabs, mussels and lobsters, are more resistant, but they too will be in danger by the end of the century. All the affected organisms build their shells or skeletons from calcium carbonate, a mineral they extract from sea water but which is attacked by carbonic acid.
( - Shellfish) and Ammonia, an alkali, would increase the pH whereas the oceans are becoming slowly more acidic (lower pH) because the additional CO2 we are dumping into the atmosphere is dissolving in the water giving carbonic acid: (Carbonic Acid)

Temperature and affect on Gas / Water
Why carbon dioxide is more soluble (the ability to dissolve in water) in cold water than it is in warm water.
All gases are more soluble in cold water than in warmer water. This is a general trend. The reason has to do with the thermodynamics of the reaction: GAS(in solution) = GAS(gas phase) The entropy change, delta S, of this reaction is always positive because the gas molecules are less constrained than the gas molecules in solution. The change in Free energy of reaction with an increase in temperature is the negative of delta S. The bottom line is that the solubility of gases decreases with increasing temperature. This effect is particularly large for gases like CO2 that undergo specific reactions with water. Ammonia would be another example.
The principle gives us the fact that a dissolved gas (carbon dioxide in this case) always becomes less soluble with increasing temperature. One can testify to this from experience that much more gas is released from a can of soda that is opened when it is warm rather than when it is cold. This illustrates that temperature effects the solubility of a gas. (Carbon Dioxide and Solubility)
Read More »

Koi, Japanese Carp

These are beautiful little fish. When I walk up to their tank they're scattered around in it, but soon conglomerate at the edge, mouths wide open, thinking they're going to get fed. Some jump out of the water, into the air (some snapshots below)... they're very active little fish, which makes them very difficult to photograph.
The word "koi" comes from Japanese. The original Japanese word koi simply means "carp," including both the dull grey fish and the brightly colored varieties. A homonym of koi means 'love, affection' and koi are therefore symbols of love and friendship in Japan; a good example is the short story Koi-san by Mukoda Kuniko. (Wikipedia)

Koi, Japanese Carp

Koi, Japanese Carp

Koi, Japanese Carp

Koi, Japanese Carp

Koi, Japanese Carp

Koi, Japanese Carp

Koi, Japanese Carp

All images, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 and 21

More Koi photos added February 2, 2007
22 23 24 25 26 27 and 27 (+/- Large) 28 29 30 31
Read More »

Constructing a CO2 Reactor


CO2 Reactor
Fig. 1 [(+/-)] CO2 reactors are used to deliver bubbles of carbon dioxide (carbonic acid) to plants growing inside an aquarium.

CO2 Reactor
Fig. 2 [(+/-)] Plants thriving inside fully aquatic environment.
CO2 Reactor
Fig. 3 [(+/-)] Pressure built up inside the CO2 Reactor pushes the gas through the small plastic tube and into the tank for circulation. A small air stone is attached at the end of the tube (see figure 13). For information on airstones, go here, Air Stones for Aquariums.

"Air stones provide very fine air bubbles, much finer than those released from a piece of tubing attached to a pump. For the aquarium keeper this means more oxygen in the water. Oxygen absorption is improved by the large surface area of the smaller bubbles. Adequate oxygen can increase the amount of fish that your aquarium can hold." (

A CO2 Reactor of this nature should begin working within 1-2 days, and should last approximately two weeks. The process to construct a CO2 Reactor involves a few simple steps and ingredients:

·Baking Soda

CO2 for plants lowers the PH level in water, and improves water quality for fish.

CO2 Reactor
Fig. 4 [(+/-)] Bottle which has been thoroughly cleansed of all liquids and fitted with plastic funnel.

CO2 Reactor
Fig. 5 [(+/-)] Granulated sugar is added.
CO2 Reactor
Fig. 6 [(+/-)] Measurements are approximate.
CO2 Reactor
Fig. 7 [(+/-)] Yeast is an important ingredient in the creation of a CO2 Reactor.

"Yeasts are unicellular eukaryotic microorganisms classified in the kingdom Fungi. Approximately 1,500 species of yeasts have been described,[1] most of which reproduce by budding, although in a few cases by binary fission. Yeasts measure about 3µm varying across species. The yeast species Saccharomyces cerevisiae has been used in baking and fermenting alcoholic beverages for thousands of years. It is also extremely important as a model organism in modern cell biology research, and is the most thoroughly researched eukaryotic microorganism, which gathers information into the biology of the eukaryotic cell and ultimately human biology." (Wikipedia)

CO2 Reactor
Fig. 8 [(+/-)] Yeast added to the mixture.

CO2 Reactor
Fig. 9 [(+/-)] A clump of Sodium bicarbonate, Baking Soda is added.

CO2 Reactor
Fig. 10 [(+/-)] Warm water is added until bottle is approximately 3/4 full.

CO2 Reactor
Fig. 11 [(+/-)] All ingredients have been added and the bottle should be capped and firmly shaken.

CO2 Reactor
Fig. 12 [(+/-)] Shaking the mixture helps sugar dissolve in the warm water. Yeast breaks down the sugar, converting it to carbon gas

...yeast causing fermentation can be detected by observation. The first indication of ferment is the appearance of tiny bubbles, which collect on the sides and the bottom of the vessel and then gradually rise to the top. These bubbles are a form of gas called carbon-dioxide, or carbonic-acid, gas. Gas, acid, and alcohol are three results of the action of the ferment. (Basics about Ferment)

CO2 Reactor
Fig. 13 [(+/-)] A small hole should be drilled through the cap, to fit the line of plastic tubing. Care should be taken to ensure this hole is no larger than the tubing or gas will leak around the line instead of being pumped through into the aquarium. Securely tighten the cap on the bottle. The bottle will be under significant pressure as chemical reactions occur over the following two weeks.
An airstone is placed on the opposing end of tubing, inside the aquarium.

Related Links to Carbonic Acid in Water
CO2 and Water Hardness
Carbonic Acid, Wikipedia
What happens when water mixes with carbon dioxide.
H2O + CO2 ->H2CO3 (carbonic acid). Hydrogen bonds to carbon instead of oxygen.
Making Carbonic Acid
Carbon Dioxide and Carbonic Acid, Chemistry Page
Chemistry and Aquaria
A series of solutions to common pH problems.
Airstones, how to clean and rejuvenate old airstones.
Read More »

Fish Anatomy


Fish Anatomy
Fish Anatomy

1000 pixels width

Fish Anatomy

Fish Anatomy
Fish Anatomy

1000 pixels width

Fish Anatomy
Fish Anatomy

1000 pixels width

Fish Anatomy
Fish Anatomy - Gills

1500 pixels width

a. general features of a spiny-rayed fish
b. adipose fin showing its location on caudal peduncle when present
c, canine teeth on jawbone (dentary) of a yellow pikeperch (Stizostedion)
d. method of counting the number of principle dorsal fin rays in soft-rayed forms such as minnows, suckers, salmonids, and allied forms
e. shows the gill or branchiostegal membranes free (left) and united (right) to the isthmus on the underside of the head
f. comparison of the dentition in the roof of the mouth of a charr (Salvelinus) with a trout (Salmo).
(Note that in Salmo the teeth extend down the shaft of the vomer while in Salvelinus they are restricted to the crest or head of this bone.)
g. position of the gill rakers and gill filaments on a single gill arch
h. main difference between cycloid and ctenoid scales. Fish with ctenoid scales such as bass, sunfish or perch feel rough in the hand while fish with cycloid scales such as trout or minnows feel slippery and are difficult to hold. The ctenii acount for the difference.
We have an individual project to do for Aquaculture Practicum for the term, and my proposed project includes:

1. Dissection of one fish purchased at local seafood market, and labeling each part according to chart/s.
2. Attempt at recreating model of the dissected fish and organs in clay, with identical labeling.
3. Research and identify function of each organ / part of fish anatomy in writing.
Additional requirement by instructor: Keep a record of all observable details.

Read More »

Catfish Production in the Hatchery

Catfish hatcheries are typically, but not always, indoors. Usually a simple pole barn or block building will suffice and elaborate structures are unnecessary. Egg hatching troughs are made of aluminum or fiberglass, and measures 12" deep, 22" wide and 8-10' in length.

Channel Catfish Eggs

The trough is usually mounted, and stand about waist high. Each egg trough is outfitted with 1/4" hardware cloth baskets in which the egg masses are suspended inside.
Catfish Hatchery Basket
Plastic paddles, designed by catfish hatchery owner Jerry Nobile of Sunflower County, can be stopped by hand and are a safer alternative to those made from metal that typically are used in hatcheries. The white paddles, which circulate water and provide oxygen to the catfish, are cut from thick plastic barrels and bent to fit around the rod that moves them.
Catfish Hatchery Safety

A paddlewheel extending the full length of the trough is slowly turned (at about 30 rpm) by a gear-motor mounted at one end of the trough. The turning paddlewheel simulates the fanning of eggs by the male catfish under natural conditions. Many producers are now using airstones placed directly under the baskets rather than paddlewheels for egg agitation, with very satisfactory results. Airstones prevent fewer hazards to hatchery workers and visitors than the gearmotor-propelled turning paddlewheels.

Catfish eggs held in flow-through water (about 8 gpm per trough) at water temperatures of 78-82 F will hatch in 5-7 days.

The newly hatched "sac-fry" are pink and attached to a large yolk sac which sustains them while they go through their final stages of development.
Catfish fry
Baby catfish (fry) possess a yolk from which they derive nourishment for the first four to five days of life and are called “sac fry.” This is how they appear under a microscope. (Photo by German Poleo)
From Preliminary Evaluation of Early-age Catfish Stocking to Enhance Louisiana Fingerling Producers’ Profitability

The sac-fry settle to the bottom of the trough and congregate, which allows them to be easily siphoned into a five-gallon bucket and moved to separate troughs.

Sac Fry

Fry-rearing troughs are identical to the egg troughs, but do not have baskets or paddlewheels. Troughs are provided with flow-through water at 8 gpm and 78-82 F, provided with aeration, usually by a small air blower system with airstones in each trough.

After several days the sac-fry are called "swim up fry", because they absorb the yolk sac, and change from pink to jet black. At this point they begin swimming at the surface in search of food. They are fed a high quality mash (45-55% crude protein and 12-16% crude fat). Swim-up fry are fed at least eight times each day. After a few days, fry are transferred to the nursery ponds for fingerling production. Easy collection from the troughs with large dipping nets, fry may be counted using the volume-displacement method. This requires a 100 ml graduated cylinder, measuring cup marked in millileters, and a counting tray:

1. Count 100 fry.

2. Place the fry in a 100 ml graduated cylinder filled with 50 ml water. Subtract 50 ml from final volume after adding the fry. Divide 100 by the number of ml of water they displace. This figure is the number of fry per ml.

3. Collect remaining fry with the dip net, and place them in a 1000 ml measuring cup that has been partially filled with water. Record the change in volume.

4. Multiply the total ml of fry by the number of fry per ml to obtain the total number of fry.

Once fry numbers estimates have been made, the fry are then transferred to nursery ponds. Be sure to slowly acclimate fry when transferring into ponds. Generally its best to stock catfish fry into ponds during the early morning, when water temperatures are at or near the daily low.

Stocking rates for fingerling production differentiate, from 30,000 per acre to 200,000 per acre, or more. A major factor in determining the stocking rate is the desired size of fingerling during harvest. The more densely the fry are stocked, the smaller the fingerlings will grow to be by Autumn. Ponds stocked at a 30,000 per acre rate will easily produce 6-8" fingerlings by the fall. Ponds stocked at greater densities than 100,000 per acre will produce small fingerlings (around 3-5" or less in size). Fingerlings of this size will not be desirable for stocking into food-fish production ponds, and most likely will be difficult to sell.

Once fry have been carefully stocked into the ponds, they should be fed twice each day through the remainder of the growing season. Start with a #1 crumble with 45% crude protein and 12% crude fat, gradually increasing the feed particle size and reducing protein and fat content. Once the fingerlings are in the 4-6" size range, they may be fed 3/16" floating pellets with 36% crude protein and 6% crude fat. The fish should be actively consuming this type of feed before transfer to foodfish growout ponds.

High water quality in fingerling production ponds is very important, since fry and fingerlings are more susceptible to poor water conditions than larger fish.

Before purchasing fingerlings, you should check the fish personally to ensure they are healthy, well-fed and of the proper size (around 6").

Check for any clinical signs of disease and if possible, obtain disease certification from a state veterinary lab maintained by the NC Department of Agriculture. (

The fish should be well fed and "filled out". Fish that appear starved, may have digested their internal organs and may never eat again.

Standard production feed for channel catfish is a floating feed with 32% crude protein and 5-7% crude fat. This feed is based on standard formulations developed by researchers at Auburn University and Mississippi State University. It is manufactured by several feed mills located throughout the catfish producing states and is widely available. Most feed and seed store in rural areas of the southeastern and mid-western US have this feed readily available in 50 lb bags. Bulk feed purchased in wholesale quantity direct from feed mills usually is considerably cheaper than bagged feed obtained at retail price. A storage bin will be required. Sometimes a feed supplier will provide a bin free of charge or at a reduced cost if you sign a contract.

Channel catfish in grow-out ponds should be fed 1-3% of body weight each day during the growing season which lasts from April to October. Depending on size of the fish, and temperature. Feed 1% or less, 1-3 days per week during winter months, November to March. Catfish will gain 18-23% body weight during this period if fed properly, and will lose weight and be stressed (with more disease problems) in spring if they are not fed through winter months. Use a 28% protein, "semi-float" feed in winter.

Maintaining good water quality in catfish production ponds is essential. Follow a regular monitoring regimen including daily DO monitoring during warmer months and weekly ammonia and nitrite measurements throughout the year.

Disease in channel catfish are varied and may occur any time throughout the year. Watch for signs of disease during spring and autumn months, when a variety of factors make disease outbreaks more likely.
Catfish: Diseases
Read More »