Effect of Feeding Frequency and One Day Fasting on Tilapia (Oreochromis niloticus) and Water Quality

The aim of this study was to investigate the effects of different feeding frequencies and one day fasting on the quality of tank water in a recirculation system and on the growth, body composition, and welfare of juvenile Nile tilapia (Oreochromis niloticus). One hundred and twenty juveniles (24±4.2 g) were fed two or four times a day, with or without a one-day fast every fourth day. Fish that were fed two or four times every day grew more than fish that fasted once a week, but there were no significant differences in food conversion rate or specific growth rate among the four treatments. Regarding body composition, fish fed four times a day, whether fasted or not, had a higher percentage of fat, while the percentage of protein was highest in fish fed four times a day with a one-day fast every fourth day. Plasma cortisol levels at the end of the trial were similar between frequencies, suggesting little effect of feeding frequency on stress level. Electrical conductivity in tank water was highest in the twice a day/fasting group and related to higher sodium (Na+) and chloride (Cl-) levels. Overall, results suggest that fasting one day a week does not affect growth efficiency and that tilapia adjust well to relative changes in feeding frequency