Population biology of Corydoras flaveolus (Siluriformes, Callichthyidae) in Passa Cinco stream, Corumbatai river sub-basin, São Paulo state, Brazil

Abstract

The aim of this work was to characterize the population of Corydoras flaveolus in Passa Cinco stream, regarding length structure, sex ratio and reproductive aspects, in accordance with drought and rainy season periods, as well as to analyze its corporal condition. Six samplings were accomplished in five different points of Passa Cinco stream (contemplating sites of orders two to six) through use of a sieve, electric fishery equipment and fish-traps. It was captured 70 individuals, composed by 35 males and 35 females. There was not significant variation in repletion degree and accumulated fat in visceral cavity of the individuals analyzed during the considered periods. The reproductive period of C. flaveolus was extensive and more intense in the rainy season due to the largest percentage of individuals with mature gonads and higher value of gonadossomatic relationship founded in that period. The average of absolute fecundity was of 137 oocytes, and the intermittent type of spawning was performed. The females were larger and heavier than males in the same lenght. There was no difference in corporal condition of both sexes between the periods considered.