Nile tilapia (Oreochromis niloticus) production in with different stocking densities and initial weights in Southern Brazil

Abstract

Fish cage culture allows intensive production in water bodies without conventional preparation for aquaculture. This is highly important to such a State as Rio Grande do Sul, which has a great amount of hydric resources, including storage reservoirs to be used in rice agriculture. The male Nile tilapia, Oreochromis niloticus Linnaeus, 1757, shows favorable conditions to be bred, besides its excellent meat quality. However, in Southern Brazil, the low temperatures can limit its growth. The purpose of this work was to study the male Nile tilapia intensive cage production viability during the hot season in Rio Grande do Sul, reaching 450 g in seven months. Two stock densities (40 and 80 fish/m³), and two initial weights (18 and 32 g) were used in a 2x2 factorial, with different replicate numbers. The production was assessed by biometry, the results showing the possibility of reaching 450 g in the required time only for the higher initial weight fishes. The stock density did not influence weight gain. The 80 fish/m³ density is more suitable because it can produce twice as much as the 40 fish/m³ density. The initial weight has influenced weight gain being 1.47 g/day and 2 g/day for the 18 and 32 g initial weight, respectively. The food conversion ratio was 3.04:1.