Impact of carbon dioxide level, water velocity, and feeding regimen on growth and fillet attributes of cultured rainbow trout (Oncorhynchus mykiss)

Production and management variables such as carbon dioxide (CO₂) level, water velocity, and feeding frequency influence the growth and fillet attributes of rainbow trout (Oncorhynchus mykiss), as well as cost of production. More information is needed to determine the contributions of these variables to growth and fillet attributes to find the right balance between input costs and fish performance. Two studies, of 84 and 90 days duration, were conducted to determine the effects of CO₂ level, water velocity, and feed frequency on rainbow trout growth, fillet yield, and fillet quality. In the first study, two CO₂levels (30 and 49 mg/L) and two velocity levels (0.5 and 2.0 body lengths/s) were tested. In the second study two CO₂ levels (30 and 49 mg/L) and two feeding regimens (fed once daily to satiation or three times daily to satiation) were tested. In the first study, after 84 days, fillet weight from high CO₂ tanks was 13.5% lower than the fillet weights of fish from low CO₂ tanks. Percent fat of fillets was higher in low CO₂ fish (P = 0.05) after 84 days and, fish from the low CO₂ treatment were larger (P