Survival and growth of milkfish ( Chanos chanos) larvae in the hatchery. I. Feeding

Abstract

Eight larval-rearing trials were conducted to evaluate the growth and survival of milkfish ( Chanos chanos) larvae under an untested feeding regime during the 1988 spawning season. The feeding regime consisted of phytoplankton, rotifers and brine shrimp nauplii. An average survival of 32.7% at 30 days posthatch was reached. Final harvest density for the eight trials ranged from 4.1 to 6.8 juveniles per 1. The percentage of survival at 30 days posthatch was found to be negatively correlated to initial stocking density ( r =−0.84, P<0.01). The greatest mortality occurred between days 5 and 10 of each 30-day trial. The temperature ranged from 25.3 to 26.5°C. Growth did not differ significantly among trials. The average total length at day 30 for each of the trials was 17.3±0.12 mm. The growth curve was expressed by the following equation: L n=0.039(day)+1.67 r 2=0.96,P<0.01 Under this feeding regime, rotifers were first observed in the digestive tract at 80 h posthatch. Growth of fed and unfed larvae did not differ until 124 h posthatch. A linear regression, relating satiation level and normal feeding to larval size during the first 11 days posthatch, was determined.