The daily feeding rhythm to demand feeders and the effects of timed meal-feeding on the growth of juvenile Florida pompano, Trachinotus carolinus

The circadian feeding rhythm of juvenile Florida pompano, Trachinotus carol inus, to demand feeders, was electronically recorded. The fish were maintai ned under artificial light-dark conditions (LD 15:9) and given continuous a ccess to food via demand bars. A distinct circadian feeding rhythm was disp layed. Food demands occurred almost exclusively (99.0%) during the light ph ase. Feeding activity was highest early in the light period and progressive ly lessened as the day progressed. The fish made significantly more food de mands during the 2-h period of maximum demand (0600-0800 h, 21.5 +/- 5.2% S EM of the total daily food demands) than during the period of minimum deman d (1800-2000 h, 6.8 +/- 2.1%) (P < 0.01, ANOVA). The maximum and minimum fo od demand periods were then used to test the effects of meal feeding time o n food consumption and growth performance in juvenile T. carolinus. The fis h were fed by hand, at either 0600-0800 h or 1800-2000 h, for 5 weeks. Duri ng the 2-h feeding period, the fish were fed 4% of their body weight (bw) i n four equal allotments, 1% bw/30 min. At the end of the study, the fish fe d in the morning, the preferred feeding time, had significantly lower bw, s horter body length and lower food conversion efficiency than the fish fed i n the evening (P < 0.05, One-way ANOVA). Results of this study indicate tha t feeding schedules that take advantage of circadian rhythms may be used to enhance growth performance of T. carolinus, and that the preferred feeding time may not necessarily be the best time for feeding. (C) 1999 Elsevier S cience B.V. All rights reserved.