Effects of live prey concentration, salinity, and weaning age on larviculture of Piaractus brachypomus reared in a recirculating aquaculture system.

This study evaluated the effects of live prey concentration (nauplii of Artemia sp.), water salinity, and weaning age on survival, growth, and stress resistance rate (Rs) of Piaractus brachypomus under larviculture in a recirculating aquaculture system (RAS). Larvae aged 6 days post-hatching (1.64 ± 0.11 mg) were distributed in 28-L tanks (five larvae L -1 ), in two RASs. The experiment was carried in a 2 × 2 × 2 factorial arrangement, as follows: two feeding strategies (sudden transition from live food to commercial food after 10 (FT 10 ) and 20 (FT 20 ) days of larviculture with Artemia); two daily initial prey concentrations (P 350  = 350 and P 700  = 700 nauplii larva -1 , these being increased every 5 days); and two water salinities (S 0  = fresh water and S 2  = 2 g of salt L -1 ). Weight (W), total length (TL), and daily specific growth rate (SGR) were evaluated after 10, 20, 30, and 40 days of larviculture. After 40 days of larviculture, survival was evaluated and a test of air exposure was performed to determine stress resistance rate (Rs). Noteworthy results during this period are the lowest specific daily growth rate (SGR) after weaning for FT 10 and the best growth results for S 2 and P 700 . After 40 days, weight (W) and total length (TL) showed effects of P, FT, and S with higher values for P 700 , FT 20 , and S 2 (P < 0.05). The interaction P × FT × S also had effects on survival and Rs at the end of the experiment, with higher survival and Rs for P 700 FT 20 S 2 (P < 0.05). Larviculture of P. brachypomus in RAS, in association with the three managements-live prey concentration P 700 , salinity S 2 , and age at feed transition FT20-promotes maximization of survival, growth, and stress resistance rate of the animals. The larviculture of P. brachypomus in RAS must be carried out with an initial concentration of live prey of 700 nauplii larva -1 , at a salinity of 2 g of salt L -1 and with the feeding transition starting in 20 days of larviculture, for maximization intensive larviculture of this species.