Growth performance of thailand tilapia and florida red tilapia raised at different stocking densities in cages placed in fish farm ponds

Abstract

The objective of this study was to test the viability of the use of low-volume cages (1 m³) placed in farm ponds and evaluates the productivity of Thailand and red tilapia submitted to different stocking densities (200, 250, 300 fish m^-3). The research was carried out at the Aquaculture Section of the Center for the Technological Development of Agribusiness - Pindamonhangaba (SP), during autumn/winter period (March to July). Two 2,400 m² earther ponds with flow of 120 L minute^-1 were used ; six cages were placed in each pond and stocked with tilapia male fry, three of them with Thailand (14.3 cm and 53.7 g) and the other three, with red (14.1 cm and 49.9 g). After 126 days of culture, only the Thailand tilapia reached close to the commercial weight (500 g). The stocking density tested in the experiments did not affect the growth of tilapia (P>0.05). However, between the two strains, both growth in length and weight of Thailand tilapia, as well as the values of relative condition factor were significantly higher than those of red (P<0.05). The final mean weight and biomass were the double for the Thailand in relation to the red one at the studied densities, making impracticable its rearing on the autumn/winter period in the Vale do Paraiba-SP. Feed conversion ranged from 1.24:1 to 1.50:1 among the densities, and survival rate was over 90% for all the treatments. The abiotic variables, with the exception of water temperature with mean value of 22.7°C, exhibited suitable values for the culture of tilapia in cages.