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

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 parts per thousand and temperature was 27 +/- 1 degrees C during the culture periods. A completely randomized design with three replicates per treatment per trial was followed. In each trial, 60 fish (5 mg, 6 mm) 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).