Reproduction of the threatened Annual Killifish <i>Austrolebias nigrofasciatus</i> (Cyprinodontiformes: Rivulidae), confined in a natural environment

Abstract

This study concerns the reproduction of Austrolebias nigrofasciatus, an endangered annual fish species endemic to the waters of the São Gonçalo channel and its tributaries in southern Brazil. Three breeding pairs confined in small cages for four weeks in their biotope were observed to produce an average of 21.5 plus or minus 12.0 eggs/week/female, with a range of 3-39 eggs/female/week. Average egg diameter was 1.51 plus or minus 0.12 mm, with abrupt changes observed throughout the period of study. The mean oviposition observed was within the range found for other killifishes and demonstrates the high fecundity rate of the species even under confinement conditions.