Aquaculture - Koi Diet

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While studying on anatomy of fish and the technical definition of "barbel" which is used for the fish sense of "smell" in location of food and whatnot, I came across this golden tidbit on another website.

The Fundamentals of Feeding Koi and Goldfish
By Stephen M. Meyer

Feeding Options
Carp and goldfish evolution has seen to it that the proper functioning of their digestive systems requires dietary variety over the long run. Monotonous diets are fine in aquaculture where fish are routinely culled out for market early in life, but ornamental pondkeeping aims for natural life spans, which places more subtle demands on fish-rearing techniques.

In this respect, no single food type, no matter how nutritious, represents an appropriate or healthy long-term diet for koi or goldfish. I doubt that any of the manufacturers of premium koi and goldfish food would claim that their products should be the exclusive diet of your fish. Therefore, you should make every effort to offer your koi and goldfish a varied diet (which does not mean different brands of pellets but rather different types of foods: vegetables, insects, etc.).

It is useful to think in terms of a base diet and a supplemental diet for your fish. The base diet provides the essential proteins, fats and most vitamins and minerals. The supplementary diet provides additional vitamins and minerals, but also other proteins and fats and, most importantly, variety.

After reading, I visted Wal-Mart and purchased some floating pellets and dehydrated "Baby Shrimp" specially formulated for Koi and Goldfish.

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Spirogyra

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Recently, the instructors at Brunswick took myself and another student to the ponds and showed us certain common elements that are important to proper pond management and care. One of the important things I learned was about filament algae, and the threat it poses to fish.

Pond with filamentous algae, at Brunswick Community College
Enlarge to full 2816 x 2112 pixels resolution


Filamentous algae, at Brunswick Community College
Enlarge to full 2816 x 2112 pixels resolution

Filamentous algae are microscopic algae that form colonies of “filaments” — hence the name. These algae are notorious for forming the large, pillow-like mats of algae that float on the surface of ponds. Common types found in Ohio include Spirogyra and Pithophora.
Disadvantages
As in the case with planktonic algae, high levels of nutrients can cause filamentous algae abundance to explode, especially in ponds lacking other aquatic plants, becoming so abundant that severe oxygen problems can result in the pre-dawn hours during July and August. Treating a severe filamentous algae problem in summer will almost certainly cause a fish kill. Ohio State University Extension Fact Sheet A-8-01, Winter and Summer Fish Kills in Ponds, provides insight into how these types of summer kills occur.
From Benefits and Disadvantages of Aquatic Plants in Ponds, Ohio State University Extension



Algae are primitive aquatic plants that differ from other plants in that they have no true stems, leaves or roots. They have a place in the overall food chain as they convert the energy of the sun into forms that can be used as a food source for other aquatic life. Algae also help to increase dissolved oxygen in water. Algae grow in both fresh and salt water systems. There are said to be over 20,000 different named species of green algae. Algae occur in three different basic forms. These are categorised as planktonic, filamentous and macrophytic.
Worldwide, there are over 400 different species of the genus Spirogyra. Spirogyra tends to show in ponds as a tangled pond scum. It is also called “water silk”, “silk weed” and “mermaid tresses”. On sunny days, the mats of spirogyra filaments usually float on the surface of the water. They are kept afloat by tiny bubbles of oxygen arising from photosynthesis. These algal mats then sink when the sun goes down and the process reverses as photosynthesis is reduced. As a result, the strands of Spirogyra consume oxygen for cellular respiration. Carbon dioxide is then produced as a waste product. Where there are thick algal mats present, large fluctuations in the dissolved carbon dioxide and oxygen levels in the water can occur. This can lead to rapid changes in the pH of the water that in turn can cause stress and even death to other organisms, eg fish, living in the water.
Blanket Weed and other Pond Algae

Spirogyra - A Filament Algae, magnified at +/- 40x











A Desmid and Spirogyra algae found in the pond sample.


A Cladoceran found among the algae sample.

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Fish Dissection

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Preliminary Student Dissection of Fish
Head and Gills -- high magnification and some microscopy of gills, and various sections from gills to head.

This is for my term project in Aquaculture Practicum. I'm closely observing details as I go through the fish and then to study about certain features and processes in fish anatomy, and last create a model/s of those important parts of a fish.

Warning: Some of the images are graphic, while others are enlightening in understanding how a fish (as a machine) works.
Some of the less graphic images are as follows:
Lens of Eyes in a Fish.

Staggered teeth growth on lower palette.

Fully expanded fish mouth.

Magnification of a Fish Gill at about +/- 100x

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Sodium Thiosulphate

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Water companies began adding Chloromites to tap water which is poison to fish. Sodium thiosulphate is used to get rid of Chloromites in tap water.

Sodium thiosulphate
Chloramine==Ammonia?

Use a standard sodium thiosulfate declorinator for both chlorine and chloramine. However, for chloramine use it double strength. Some (and I am being cagey here) products designated to neutralize chloramine are known by their manufacturers to be toxic to fish at concentrations higher than that recommended on the bottle. ie, you have to be fairly precise. The old standard however is very forgiving. No one advertises this as it is likely to hurt sales. Moderate plant growth will take care of any excess ammonia released by the application of sodium thiosulfate to chloramine.
Declorinators (like thiosulfate) will break the chlorine + ammonia bond and set the ammonia free (so as I am told). This replaces toxic choraimine with potentially toxic ammonia. Now, extra thiosulfate will handle the free clorine. So, that leaves the ammonia...

The concentration of the released ammonia will be related to the concentration of the original chloramine. The resultant ammonia concentration is something similar to the chloramine concentration. So, I think we are talking about 1 to 2 ppm (mg/l) of ammonia (to be diluted according to the % water change). For 50 % change you can have 1 ppm of ammonia. The amount of this that is toxic to fish will depend mostly on pH but also on temperature. (There is an equilibrium between toxic NH3 and non-toxic NH4). Worst case is high pH and high temperature. At 8.5 pH and 86 deg, 20 percent would be toxic NH3 (~ 0.2 ppm). This is a lot and roughly corresponds to lethal dose for 1-hr exposure.
• Ideally fish should be diagnosed by an authorised or qualified technician.
• Carefully calculate dose rates according to manufacturers label.
• Remember that some chemicals may not be approved for use with fish that are for human consumption.

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Biological vs Mechanical Filters

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Here's something interesting I learned this week in Aquaculture Practicum, from John (BCC Instructor).

A biological filter contains bacteria which convert ammonia to nitrite and nitrobactor converts nitrite into nitrate. Nitrate is plant fertilizer, which is much less toxic than nitrite.

Ammonia occurs naturally in the environment. A small amount of ammonia is generated when lightning strikes and reaches earth in rainfall. But most ammonia is produced by bacteria in water and soil as an end product of plant and animal waste decomposition. It is found in relatively low nontoxic concentrations in soil, air, and water and provides a source of nitrogen for plants.
In soils and water ammonia will go through many complex biochemical transformations. These transformations constitute what is commonly known as the nitrogen cycle.
Ammonia in Water
Water reacts with ammonia to form ammonium and hydroxide ions. Ammonia is often referred to as “unionized ammonia”. Ammonia is toxic to aquatic organisms but ammonium is non-toxic. There exists an equilibrium in water between the toxic ammonia and the non-toxic ammonium. The equation shifts back and forth depending upon existing or introduced environmental changes.
NH3 (aq) + H2O (l) NH3 · H2O (aq) NH4 + (aq) + OH - (aq)
(Ammonia in water) (ammonia+water) (ammonium + hydroxide ions)
The dynamic equilibrium between NH3 and NH4 + is affected by water temperature and pH (acidity). At a pH of six the ratio of ammonia to ammonium is 1 to 3000 but decreases to 1 to 30 when the pH rises to eight (becomes less acidic). Warm water will contain more toxic ammonia then cooler water. When sampling water for ammonia analysis both the temperature and the pH of the surface water body must be measured at the same time the water samples are collected. (See “Ammonia, pH and Temperature Calculator”)
If ammonia is directly spilled into surface water or if water used by a fire department to depress an ammonia vapor cloud is allowed to reach surface water, aquatic life can be harmed. Even at a concentration of 0.02 mg/L (48 hour LC50) unionized ammonia is lethal to some sensitive freshwater fish. That equates to about ½ a cup of unionized ammonia in one million gallons of water. Ammonia is also highly toxic to freshwater invertebrates having a 48-hour LC50 of 0.66 mg/L for Daphnia magna . Again, water contaminated with fertilizer ammonia should not be allowed to enter any storm drains, rivers, drainage ditches, wetlands or lakes.
From Ecological Effects of Ammonia

A mechanical filter stops all solids.


Biological Filters

John explains this is both a biological and mechanical filter

Biological Filter

Mechanical Filter
From What Is A "Biological Filter"?
By Stan and Debbie Hauter
Your Guide to Saltwater Aquariums.
The biological filter in a saltwater aquarium is nothing more than a place for bacteria to grow. Any surface in an aquarium which comes in contact with tank water and the nitrobacter & nitrosomona bacteria species that you created when you cycled the tank is part of your bilogical filter. The velocity of the water passing over the bacteria also affects the efficiency of the biological. The faster the water moves over the bacteria, the more efficient it is, up to the point where the bacteria is being stripped from the filter surface.
The efficiency (strength) of a biological filter is determined by its surface area and the amount of water passing over it. Some filter medium are more efficient than others. Aquarium glass surface area aside, here are the most popular biological filtration methods:

Canister Style Filters come in many different styles and sizes and can also be multifunctional.
Live Rock / Berlin Systems are the filters of choice for many SW aquarium purists.
Live Sand / Jaubert Systems are also very popular with many reef aquarists.
Undergravel Filters are among the first biological filters created for SW aquarium hobbyists.
Wet / Dry Trickle Filters were the next step after the UGF to dramatically improve efficiency.
Biological Filtration Polls show you which biological filters are popular with other habbyists.
Choosing Your Biological Filter Material shows you which materials are more efficient.
Knowing how each biological filter works and what it requires will make Choosing a Filtration System In 5 Easy Steps much easier.

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Lowering pH Levels in Water

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As a follow-up to my earlier post, on pH levels and water

Water samples which indicate a high pH level when tested, 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.

Here's John straining the brackish water.

Large debris are removed by hand, then strained through a fine net tightened down with a bungee cord (pulley) on a large bucket.


Brackish water, (low pH solution added to one of the empty tanks). John (instructor of Aquaculture Practicum at BCC) warned it wouldn't be good for fish to be swimming in their tank and suddenly the pH drops an entire point, so the transition is accomplished gradually.

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