Aspectos reprodutivos de Phalloptychus januarius (Hensel, 1868) (Cyprinodontiformes, Poeciliidae) da Laguna Rodrigo de Freitas, Rio de Janeiro, Brasil

Abstract

From August 1997 to July 1999 5.760 specimens of Phalloptychus januarius (Hensel, 1868) were collected in the Rodrigo de Freitas Lagoon. Some reproductive aspects, such as male and female proportion, female first pregnancy size, different stages of embriologic development, and reproductive activity were studied. The results showed that the female / male proportion was 3,35:1. First maturation was observed since 19 mm total length, and the reproductive period occurred through out the year. The embryos showed four different embryonic stages until the age of birth. The male’s sexual dimorphism could be observed from 15 mm total length.