Food restriction in larviculture of Colossoma macropomum (Cuvier, 1818) reared in varying salinities

ABSTRACT Given the growing demand for tambaqui (Colossoma macropomum), economically sustainable protocols that guarantee quality in the larval stage are highly needed. Larviculture in low salinity environment can be used to reduce the daily rate of feeding, thus reducing costs. Food restriction can cause a decrease in fish growth, but it does not impair their capacity to grow if adequate feeding conditions are reestablished and if restriction is not held for too long. This study aimed at evaluating the effects of live food restriction on the growth performance and muscle morphometry of tambaqui larvae reared in different salinities. The 9,600 larvae were distributed in sixteen 60 L tanks, in a 2x2 factorial design, with two treatments, 0 and 2 g L-1 salinity (S0, S2) with food restriction of 50% (FR 50%) and without food restriction (FR 0%) of Artemia nauplii. After 15 days, no interactions were observed between the factors evaluated for production performance and muscle fibers of classes 10, 30, 40 and 50. However, the analysis of isolated factors demonstrated that the lower feeding rate reduced the performance of the larvae, while water salinity positively influenced performance and survival variables, and increased muscle fiber hyperplasia of class 20 in larvae submitted to food restriction. We conclude that live food deprivation of up to 50 % for tambaqui larvae reduces performance rates without compromising survival. To maintain growth performance and development of skeletal muscle, saline water (2g.L-1) can be applied for tambaqui larviculture in situations of live food scarcity.