Larvae of Nile tilapia lines subject to feeding frequencies under low temperature

SUMMARY The adequate food management associated with animals with higher yields and resistance to specific environments, such as waters with temperatures below the appropriate temperature, are determinant for a higher productivity. Therefore, the aim of this study was to compare larviculture performance of two strains of Nile tilapia (Oreochromis niloticus) submitted to different feeding frequencies with temperature below the optimum range for growth. Larvae of Thai (720 individuals with weight of 24.3 mg and total length of 12.4 mm) and GIFT strains (720 individuals with weight of 22.5 mg and total length of 12.0 mm) were distributed into 24 aquariuns-4L, the density of 15 larvae. L−1, 60 larvae aquarium−1, under constant aeration, natural photoperiod and temperature of 23 °C, with recirculation and thermostat. The fish were subjected to three feeding frequencies: 2, 5 and 8 times.day−1 in a randomized design in a 2 strains x 3 frequencies factorial scheme, with four replicates each. Except the temperature the other parameters of water quality, ammonia, nitrite, nitrate, turbidity, conductivity and pH, remained adequate for the species. The Thai lineage showed higher total and standard length, weight, Fulton condition factor, survival and biomass, than GIFT. The feeding frequency 5 times.day-1 led to higher values larvae in weight, standard and total length in relation the frequency of 2 times.day-1 but, when compared values of frequency 8 times.day-1 was not difference. In the temperature 23 oC, Thai strain fed 5 times.day-1 should be used.