(Pimelodus maculatus Lacépí­¨de, 1803 (osteichthyes, Pimelodidae), from stretches of Jaguarí­­ and Piracicaba Rivers, São Paulo í Brazil)

Abstract

The purpose of this study was to provide information on some aspects of the behavior of Pimelodus maculatus Lacépí­¨de, 1803, in approximately 120 kilometers of the Jaguari and Piracicaba rivers. This investigation was undertaken between July 1972 and June 1973. The area under study was divided into three sectors and, in fortnightly samplings, 674 individuals of both sexes were obtained. The results indicated that the overal sex ratio is about 1:1 when considered the total of the individuaIs, but varies significantly from one sector of the river to another. The females attain greater age, length and weight than the males and the relation weight/length differs significantly between both sexes. The results indicated that the individuaIs in this area of study show spacial distribution, related to their stages of development.