RESUMO O tambaqui, Colossoma macropomum, é uma das espécies mais produzidas na piscicultura brasileira, o que tem impulsionado o desenvolvimento de novas tecnologias para aumentar sua produtividade. O objetivo deste estudo foi avaliar o desempenho da produção de dois estoques de tambaqui de segunda geração melhorada geneticamente para ganho de peso em um sistema de criação semi-intensivo, e avaliar sua influência no custo total de produção. Foram analisados 300 peixes (peso e comprimento padrão inicial médio de 160 g e 17 cm, respectivamente) de duas famílias (A e B, 150 peixes cada). Os peixes foram marcados individualmente com microchips e estocados em um tanque escavado de 800 m2. Para análise econômica, os dados de desempenho obtidos foram extrapolados para uma piscicultura com 10 ha de lâmina d’água, adotando a metodologia Custo Total de Produção. Depois de 270 dias de cultivo, os peixes da família B foram significativamente superiores (p < 0,05) para todos os parâmetros de desempenho analisados (peso final = 1965,0 g; ganho de peso = 1786,7 g; ganho de biomassa = 255,2 kg) e crescimento morfométrico em relação aos peixes da família A (peso final = 1881,0 g; ganho de peso = 1737,5 g; ganho de biomassa: 217,7 kg). As estimativas de custo total de produção indicaram que os peixes da família B permitiriam uma redução de 4% no custo fixo médio e uma redução de 1% no custo médio total de produção.

ABSTRACT Tambaqui, Colossoma macropomum, is one of the most produced species in Brazilian fish farming, which has boosted the development of new technologies to increase its productivity. The aim of this study was to evaluate production performance in two second-generation tambaqui stocks selectively bred for weight gain in a semi-intensive rearing system and assess its influence on total production cost. We analyzed 300 fish (initial mean weight and standard length of 160 g and 17 cm, respectively) of two families (A and B, 150 fish each). The fish were individually marked with microchips and stocked in an 800-m2 excavated pond. For economic analysis, the obtained performance data were extrapolated for a fish farm with a 10-ha pond, adopting the Total Production Cost methodology. After 270 days of farming, the fish from family B were significantly superior (p < 0.05) for all analyzed performance parameters (final weight = 1965.0 g; weight gain = 1786.7 g; biomass gain = 255.2 kg) and morphometric growth in relation to the fish from family A (final weight = 1881.0 g; weight gain = 1737.5 g; biomass gain: 217.7 kg). The total production cost estimations indicated that fish from family B would allow for a 4% reduction in the average fixed cost and a 1% decrease in the total average production cost.

Performance and economic indicators of a large scale fish farm that produces round fish, located in Mato Grosso State, Brazil, were evaluated. The 130.8 ha-water surface area was distributed in 30 ponds. Average total production costs and the following economic indicators were calculated: gross income (GI), gross margin (GM), gross margin index (GMI), profitability index (PI) and profit (P) for the farm as a whole and for ten ponds individually. Production performance indicators were also obtained, such as: production cycle (PC), apparent feed conversion (FC), average biomass storage (ABS), survival index (SI) and final average weight (FAW). The average costs to produce an average 2.971 kg.ha-1 per year were: R$ 2.43, R$ 0.72 and R$ 3.15 as average variable, fixed and total costs, respectively. Gross margin and profit per year per hectare of water surface were R$ 2,316.91 and R$ 180.98, respectively. The individual evaluation of the ponds showed that the best pond performance was obtained for PI 38%, FC 1.7, ABS 0.980 kg.m-2, TS 56%, FAW 1.873 kg with PC of 12.3 months. The worst PI was obtained for the pond that displayed losses of 138%, FC 2.6, ABS 0.110 kg.m-2, SI 16% and FAW 1.811 kg. However, large scale production of round-fish in farms is economically feasible. The studied farm displays favorable conditions to improve performance and economic indicators, but it is necessary to reproduce the breeding techniques and performance indicators achieved in few ponds to the entire farm.