GROWTH AND REPRODUCTIVE-PERFORMANCE OF BIGHEAD CARP (ARISTICHTHYS-NOBILIS) REARED WITH OR WITHOUT FEEDING IN FLOATING CAGES

Bighead carp (10.5 months old) stocked in cages in Laguna de Bay were assigned the following feeding treatments: 1. 40% protein diet, 2. 20% protein diet, and 3. no artificial diet (control), to determine the effects of feeding on growth and reproduction. The fish were fed for 15 months. Growth was monitored for the first 9 months and fish were induced to spawn in the succeeding months. Both weight gain and increase in total length did not differ significantly (P > 0.05) among treatments. Results of the induced spawning showed that fish fed the 40%-protein diet had the highest mean total weight of eggs/female, total number of eggs/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 the same parameters. However, mean fertilization rates (54-58%) and hatching rates (61-78%) were not significantly different (P > 0.05) among treatments. The mean number of 3-day old fry of fish fed the 20%-protein diet (48 085) was lower than that of fish fed the 40%-protein diet (86 806). The control fish gave a significantly low (P < 0.05) number of 3-day old fry (37 469). When deprived of food for up to 10 days, fry of the fed broodstock had a lower mortality rate than fry of the control fish.