Effect of prepared diet and vitamins A, E and C supplementation on the reproductive performance of cage-reared bighead carp Aristichthys nobilis (Richardson)

Twenty-month-old bighead carp, Aristichthys nobilis (Richardson), were fed prepared dry diets for 20 months in cages in Laguna de Bay, Philippines, to determine the effect on reproductive performance. The experimental diets w ere similar in composition except for the combinations of vitamins being te sted. Diet 1 was supplemented with vitamins A, E and C; diets 2, 3 and 4 ea ch lacked one of the supplementary vitamins; and diet 5 did not include any vitamin supplementation. Bighead carp that relied solely on natural food w ithout a prepared diet served as a control. The total of six treatments eac h had two replicates. Results showed that the onset of gonad maturation was 2-3 months earlier in the fish that were fed the prepared diets regardless of vitamin supplementation, when compared with the fish that were fed natu ral 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 tho se fish that were fed natural food (control) (36.5 +/- 31.3%). Mean number of 3-day-old larvae was highest in fish fed on diet 1 (34 525 +/- 1732), fo llowed closely by fish that were fed diet 3 (32420 +/- 3909). A low number of 3-day- old larvae was obtained from fish fed the natural diet (14 490 +/ - 4331) as well as in fish that were fed diet 2 (-vitamin Al 14 347 +/- 486 3), 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 (P > 0. 05) among treatments. The addition of vitamins also had no significant effe cts on weight gain of adult fish.