Observations on the Culture of Flathead Catfish (Pylodictis Olivaris) Fry and Fingerlings in Troughs

Flathead catfish fry were reared to fingerling size in troughs by starting them to feed on shrimp, and marine fish. Other foods that were subsequently eaten by fry and fingerlings included beef liver, spleen, eggyolk, cheese, canned dog food, canned salmon, and some dry cereal feed. The food was prepared by placing the meats in a blende, adding a small amount of water, and stirring until the food was “creamy” in texture. After approximately three weeks, the fish had increased in size so that they could consume the food passed through a food chopper. No feeding was attempted until the yolk sac had been absorbed and the fish exhibited feeding behavior. After two or three days, if not fed, the fry will not feed even though food is offered. The food was placed (with a pipette or by rubbing between fingers) in the water above the fish. Since the fish lost interest in the food as soon as it reached the bottom of the trough, that amount of food that could be consumed before it fell to the bottom and lost was considered the optimum portion. Initially, these fish were fed frequently during the daylight hours; but after about three weeks, the number of feedings was decreased to four daily. Initial mortalities from non-feeding individuals were estimated to be less than 10 percent, while the total observed mortality up to 110 days after hatching was estimated to be less than 20 percent, although accurate records were not kept. Unobserved losses may have exceeded 50 percent. Some of these losses were contributed to cannibalism, but the majority were contributed to predators (rats, mink). Since the purpose of the experiment was only to determine if flathead catfish could be raised in troughs on artificial food, the records on age and growth, food conversion, and other experimental data were not kept. At the conclusion of the experiment, approximately 110 days after the eggs hatched, the fish had reached three to four inches in length and were apparently in “good” condition. However, the rate of growth, degree of cannibalism, and maximum size that can be attained in troughs may be influenced by rate of stocking, frequency of grading, etc. Therefore, if these species proves to be of value in fisheries management, much additional research should be conducted on its culture.

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