Effect of dietary fatty acids on growth of milkfish Chanos chanos fry in brackish water

Abstract

Five purified microbound diets containing 1% of 18:2n − 6, 18:3n − 3, 20:4n − 6, or n − 3 highly unsaturated fatty acids (HUFA: 60% 20:5n − 3 + 40% 22:6n − 3) in addition to 8% 18:1n − 9, and a control diet containing 9% 18:1n − 9 were fed to milkfish fry or late postlarvae for 30 days (Trial 1) and 35 days (Trial 2). The salinity was 16–17‰ and temperature was 27 ± 1 °C during the culture periods. A completely randomized design with three replicates per treatment per trial was followed. In each trial, 60 fish (5mg, 6mm) were stocked per 301 oval plastic tank and fed the experimental diets at 20% of biomass per day.

Survival of 100% observed for all groups in both trials demonstrated that the milkfish fry reared in brackish water utilized the test diets. Specific growth rates did not differ significantly among treatments (P 0.05), with values of 9.5–9.9% and 10.0–10.3% in Trials 1 and 2, respectively. Weight, length and feed conversion ratio of milkfish fry fed the various diets also did not differ significantly (P 0.05). Although not significantly differentiated in Trial 1 (P 0.05), incidence of eye abnormality was highest in milkfish fry fed the 18:1n − 9 diet in Trial 2 (P 0.05).