(Reproductive cycle of Brazilian catfish, Rhamdia hilarii (Valenciennes, 1840). (and its relation with environmental factors.)

Abstract

The purpose of this study was to know the reproductive cycle of a Brazilian catfish, Rhamdia hilarii in its natural environment. The specimens were collected in Jaguari River, São Paulo State. Morphological changes in the ovaries and testis were studied. It was possible to establish six stages: immature, resting, maturation, reproduction, partially spent and spent by macroscopic and microscopic appearance of the gonads as well by analysis of variation of individual values of gonadosomatic index (GSI). Females and males of this species spawn during the spring and summer months. The maturation process occurs when the water temperature is about 17°C and the start of spawning coincides with the increase of the values of the abiotic factors.