Cage culture of tambaqui (Colossoma macropomum) in a central Amazon floodplain lake

Tambaqui, Colossoma macropomum, a native fish species of the Amazon basin, has been tested in cages placed in floodplain lakes with promising results. The present study evaluated culture performance and economic feasibility of tambaqui raised at different stocking densities in cages placed in a central Amazon floodplain lake. Fish were stocked in triplicate 6-m3 cages at 20, 30, 40 and 50 fish/m3. Fish were fed a 34% crude protein (CP) extruded feed six days a week during the first two months and a 28% CP extruded feed for six months. The experiment lasted for 240 days. Mean survival rates were over 97% and were not significantly affected by fish density. Tambaqui growth rate and weight gain were not affected by the tested densities. Fish growth rate did not decline during the culture period, indicating that fish carrying capacity per cage was not reached. Fish hematological parameters, as well as, glucose, cortisol and ions did not show significant differences among the four tested densities. Fish raised at 40 and 50 fish/m3 had significantly lower feed conversion ratio (FCR) than fish stocked at 20 or 30 fish/m3. FCR presented an inverse relationship to stocking density, with lower FCR at higher densities. Economic sensitivity analysis showed that economic performance of tambaqui raised in cages is more sensitive to sale price then to feed cost. To increase fish yield/m3, higher stocking densities should be tested.