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.
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.
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.
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. (http://www.ncvdl.com/)
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.