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 carolinus, to demand feeders, was electronically recorded. The fish were maintained under artificial light-dark conditions (LD 15:9) and given continuous access to food via demand bars. A distinct circadian feeding rhythm was displayed. Food demands occurred almost exclusively (99.0%) during the light phase. Feeding activity was highest early in the light period and progressively lessened as the day progressed. The fish made significantly more food demands during the 2-h period of maximum demand (0600-0800 h, 21.5 +/- 5.2% SEM of the total daily food demands) than during the period of minimum demand (1800-2000 h, 6.8 +/- 2.1%) (P < 0.01, ANOVA). The maximum and minimum food demand periods were then used to test the effects of meal feeding time on food consumption and growth performance in juvenile T. carolinus. The fish were fed by hand, at either 0600-0800 h or 1800-2000 h, for 5 weeks. During the 2-h feeding period, the fish were fed 4% of their body weight (bw) in four equal allotments, 1% bw/30 min. At the end of the study, the fish fed in the morning, the preferred feeding time, had significantly lower bw, shorter body length and lower food conversion efficiency than the fish fed in the evening (P < 0.05, One-way ANOVA). Results of this study indicate that 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 Science B.V. All rights reserved.