Growth curve of selectively bred and non-selectively bred tambaqui (Colossoma macropomum).

The aim of this study was to evaluate the growth curve of selectively bred and non-selectively bred tambaqui (Colossoma macropomum). The experiment involved 388 fish (weight: 65.38 ± 20.00 g; age: 217 days), consisting of 252 fish from seven selectively bred families (18 fish per family) and 18 non-selectively bred fish (control group). Groups were placed in two 800-m² tanks. Biometric measurements were taken on nine occasions at 30-day intervals, for a period of 254 days. Weight and morphometric traits were evaluated. To describe the tambaqui growth behavior, we adopted the Gompertz nonlinear regression model. Greater growth (p < 0.05) was observed in selectively bred families compared with control group. Four families stood out with higher (p < 0.05) asymptotic values for weight (F1: 2448.7 g; F7: 2284.7 g; F5 2180.1 g; F4: 2080.5 g; and control: 1808.4 g) and other morphometric traits. None of the selectively bred families (except F5) had a higher growth rate and age at inflection point than the fish from control group. In conclusion, selectively bred and non-selectively bred fish present distinct growth curves, but some families have greatly superior growth.

Weight and body yield of selectively bred tambaqui (Colossoma macropomum) farmed in different environments.

The objective of this study was to evaluate the weight and body yield of two families of selectively bred tambaqui farmed in different environments. Two families (FA and FB) were reared in the municipalities (environments) of Santo Antônio de Leverger (MT) and Campo Grande (MS) for 431 days. Pre-bleeding weight, body yield, and the interaction effect between families and environments on these traits were investigated. No interaction effect between the evaluated families and environments was detected on the evaluated traits. Pre-bleeding weight did not differ significantly between the families in MT (FA: 2,421.7g; FB: 2,478.0g) or in MS (FA: 1,138.7g; FB: 1,389.8g), but the fish from MT had a higher (P<0.05) pre-bleeding weight than those farmed in MS. The visceral fat yield (considering the two environments) was higher (P<0.05) in FB family (3.8%) than in FA family (3.3%).Fish from MS showed higher (P<0.05) offal yield (10.6%) and visceral fat yield (3.9%) but a lower clean-trunk yield (70.6%) than the tambaqui farmed in MT (offal: 7.7%; visceral fat: 3.1%; and clean trunk: 72.6%). In conclusion, the MT environment provides higher pre-bleeding weight and clean-trunk yield and lower offal and visceral-fat yields than the MS environment.

Performance and economic viability of tambaqui, Colossoma macropomum, selectively bred for weight gain

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. (AU)