Rearing of Arapaima gigas (Teleostei, Osteoglossidae) in hothouse and closed water circulation system in State of São Paulo, Brazil

Abstract

In order to know the performance of pirarucu (Arapaima gigas Cuvier, 1817), three compartments of 30 m³ each one, into a 186 m³ tank, were used. The tank was provided with water biological filtration, closed water circulation system, shelter of hothouse, and wood-burning oven. The 89 fishes, which initially exhibited 134.04 ± 20.74 g of weight and 26.53 ± 1.32 cm of length, were stocked for 16 months at a density of 0.96 fish/m³ and fed with extruded ration (40% CP). The mean weight and length obtained were 7,917.20 ± 963.55 g and 96.78 ± 3.23 cm, respectively. The equations which represent the growth are: Wt = 12,107 (1- e^-0.1214.t) 3.147 (r² = 0.9626); Lt= 107.51 (1- e^-0.1214.t) (r = 0.9696), and Lt = 0.0049 Wt^-3.147 (r² = 0.9982), for the growth in weight, growth in length, and weight-length relationship, respectively. The value of the relative condition factor (Kn) was 1.002 ± 0.072 and that of the apparent feed conversion was 2.64. The mean water temperature was between 26.23 ± 1.50 and 32.37 ± 1.33°C. The maximum values of alkalinity (164.19 mg CaCO₃/L), calcium (40.00 mg Ca⁺²/L), total ammonia (15.20 mg NH₄⁺/L) and non-ionized ammonia (0.84 mg NH₃/L) were higher than those usually recommended for fish rearing. The conclusion was that the rearing of A. gigas in the State of São Paulo may be considered as a new alternative to the production of fish destined for human consumption.