Reproductive Cycle of a Population of the Guaru, Phallocerus caudimaculatus (Poeciliidae), in Southeastern Brazil

The reproductive cycle, size/fecundity relationships and seasonality in the reproduction of the poeciliid Phallocerus caudimaculatus were studied in Southeastern Brazil. There was a positive correlation between the monthly proportion of females with offspring and the day length and between female’s size and offspring number. The reproductive period starts in November, when most of the females carry embryos. From January to March a decrease was observed in the number of females carrying eggs and an increase in the number of the non-reproductive females. Greater microhabitat availability, food supply and warmer temperatures may provide optimal conditions for growth of juvenile P. caudimaculatus in the wet-warm season.