Stocking density and water salinity on pacamã larviculture

Abstract

The objective of this work was to evaluate the effect of stocking density and water salinity levels on Lophiosilurus alexandri (pacamã) larvae rearing fed with Artemia sp. nauplii. Three stocking densities were used: 20, 40 and 60 larvae L^-1 (D₂₀, D₄₀ and D₆₀, respectively). For each density, three different levels of salinity were tested: freshwater (S₀), 2‰ (S₂) and 4‰ (S₄), in a completely randomized design, in a 3x3 factorial scheme, with three replications. The growth, survival, mortality, cannibalism, production and nonionized ammonia levels were evaluated. The nonionized ammonia levels were higher at D₄₀ and D₆₀. At 10 days of feeding, the weight was affected negatively in D₄₀ and D₆₀ associated to higher water salinity (S₄). The higher survival was verified in D₂₀S₂ treatment, while smaller values were found in S₄, regardless of the density used. Small mortality rate and no cannibalism were observed. The juvenile final production was also influenced by the evaluated variables. Larvae of L. alexandri can be reared, during the first ten days of exogenous feeding, in freshwater or slightly saline water (2‰) with higher juvenile production at density D₆₀