Effect of prepared diet and vitamins A, E and C supplementation on the reproductive performance of cage-reared bighead carp Aristichthys nobilis (Richardson).
Caged 20-month-old bighead carp, Aristichthys nobilis, were fed prepared dry diets for 20 months (February 1993 - October 1994) in Laguna de Bay (Philippines) to determine the effects on reproductive performance. The experimental diets were similar in composition except for the combinations of vitamins being tested. Diet 1 was supplemented with vitamins A, E and C; diets 2, 3 and 4 each lacked one of the supplementary vitamins; and diet 5 did not include any vitamin supplementation. Bighead carp that relied solely on natural food without a prepared diet served as control. Each of the six treatments had two replicates. Results showed that the onset of gonad maturation was 2-3 months earlier in the fish that were fed prepared diets regardless of vitamin supplementation, when compared with fish that were fed natural food (control). Moreover, the prepared diets enhanced egg hatchability, which was significantly higher in fish that were fed diet 1 (+vitamins A, E and C, 80.5±18.1%) and diet 3 (-vitamin E, 78.5±1.1%) than in those fish that were fed natural food (control, 36.5±31.3%). Mean number of 3-d-old larvae was highest in fish fed on diet 1 (34 525±1732), followed closely by fish that were fed diet 3 (32 420±3909). A low number of 3-d-old larvae was obtained from fish fed the natural diet (14 490±4331), as well as in fish that were fed diet 2 (-vitamin A, 14 347±4863), diet 4 (-vitamin C, 21 407±5840) and diet 5 (-vitamin A, E and C, 12 191±1439). Other criteria for reproduction, such as relative fecundity, fertilization rate and hatching rate did not differ significantly among treatments. The addition of vitamins also had no significant effect on liveweight gain of adult fish.