Effects of water temperature and dissolved oxygen on daily feed consumption, feed utilization and growth of channel catfish (Ictalurus punctatus)

Feed intake (Fl), feed efficiency (FE), protein efficiency ratio (PER) and weight gain (WG) of juvenile channel catfish initially weighing 15.0 +/- 0.23 g (10-12 cm initial total length) were evaluated under three regimes of time-varying water temperature (mean daily water temperature for Stoneville, MS, USA; mean +3; and, mean -3 degrees C) and three of dissolved oxygen (DO; 100, 70 and 30% air saturation, at each temperature). Two independent experiments lasting 6 and 8 weeks, respectively, simulated spring and fall temperature and photoperiod patterns. Temperature-oxygen regimes were applied to randomly assigned duplicate 110-1 aquaria with individual biofilters. Fish were fed once daily, to slight excess, a commercial catfish floating feed. After 45 min, uneaten feed was collected, dried and weighed; then FI was calculated by difference. Fish in each aquarium were weighed collectively, biweekly. In both experiments higher temperatures and higher DO levels produced increased feed consumption. A multivariate regression model was fitted to the data to describe the combined effects of temperature and DO on FI. There was a progressive reduction in Fl as DO declined from 100 to 30% air saturation. In both trials weight gain was higher for fish held 3 degrees C above the mean water temperature at 100% air saturation values of DO; whereas, the lowest values of WG were obtained for fish held at 30% air saturation and 3 degrees C below the mean water temperature. Weight gain increased with temperature, with maximum rates reached at 27.1 degrees C with DO equivalent to 100% air saturation. In contrast, when DO was 30% air saturation, growth rates plateaued as ambient temperature exceeded 22.8 degrees C. This model will assist in optimization of feeding practices in channel catfish aquaculture. (C) 2000 Elsevier Science B.V. All rights reserved.