Competitive Feeding Interactions between Small and Large Channel Catfish Cultured in Mixed-Size Populations

Abstract

Production of channel catfish Ictalurus punctatus in ponds may be affected by competitive feeding interactions between large fish that remain after incomplete harvest and small fish that are stocked following harvest. To study the effect of channel catfish size on competition for feed, we examined consumption by feeding colored feeds sequentially to fish held either in raceways or ponds. Colored feeds were created by adding pigments to a floating catfish feed (35% crude protein). A preliminary study showed no significant differences in consumption of the colored feeds, suggesting no selection for color. Following a 2-week conditioning period in the raceway or pond, mixed-size fish populations were fed a red and green feed sequentially at 1% body weight for each. Fish were subsequently sacrificed and red and green colored feeds were separated from the stomach contents. In the raceway, small fish consumed a significantly higher mean percentage of red feed (59.3%) than large fish (50.4%). In an unreplicated pond trial, mean percentage of red colored feed consumed by small fish (45.8%) was not significantly different from that consumed by large fish (44.8%). Results suggest that small fish in mixed-size populations are not competitively disadvantaged by large fish during feeding activities.