Growth and reproductive performance of bighead carp (Aristichthys nobilis) reared with or without feeding in floating cages.
72 bighead carp, 10.5 months old, stocked in cages in Laguna de Bay were assigned to feeding with a 40%- or a 20%-protein diet for 15 months, or were not fed (controls). Growth was monitored for the first 9 months and fish were induced to spawn by injection of LHRH plus HCG in the succeeding months. Weight gain and increase in total length did not differ significantly among the 3 groups. Fish fed the 40%-protein diet had the highest mean total weight of eggs per female, number of eggs per spawning, and number of eggs/kg body weight. Fish fed the 20%-protein diet had intermediate values while the control fish had the lowest values for these traits. However, mean fertilization rate (54-58%) and hatching rate (61-78%) were not significantly different among treatments. Fish fed the 40%-protein diet produced more fry than those fed the 20%-protein diet, and fish that were fed produced more fry than the unfed controls (values were significant different for the 40%-protein groups vs. controls). When deprived of food for up to 10 days, fry of the fed fish had a lower mortality rate than fry of the control fish.