Induced reproductive responses of the neotropical anostomid fish <i>Leporinus elongatus</i> Val. under captive breeding

Abstract

Experiments on induced spawning of the anostomid fish Leporinus elongatus Val. 1849, an important neotropical migratory fish, were carried out at Três Marias Fish Hatchery Station, State of Minas Gerais, Brazil, to develop a reliable protocol for inducing breeding in this species. L. elongatus matures reliably in earthen ponds to a point at which final maturation can be induced with carp pituitary extract. The following data were recorded: number of extruded eggs (g ova−1) = 2444 ± 740; stripped ova weight:body weight = 13.1 ± 2.9%; retained (ovulated but not stripped) ova weight:body weight = 5.8 ± 2.6%; initial fertility = 318.7 × 103± 149.2 × 103; final fertility = 229.3 × 103± 129.3 × 103; egg fertilization rate = 63.8 ± 16.4% and ≈ 229 000 larvae per female. The relationships between stripping time and water temperature and between hatching and water temperature were given by the same exponential equation t= ae–bT. The relationships between body weight (Wt) and initial (IF) and final fertility (FF) were expressed by the equations: IF =−9382 + 322 047 × Wt (r2= 0.84); FF =−40 780 + 265 062 × Wt (r2= 0.75).