Population structure of Rhamdioglanis frenatus (Siluriformes: Heptapteridae) in the Itatinga River Basin, SP Vinícius Estrella Silva Carvalho, Victoria Pinheiro Gonçalves da Silva, João Alberto Paschoa dos Santos, Ursulla Pereira Souza

Abstract

 Fish of the Genus Rhamdioglanis are found in streams from rocky bottoms to regions with moderate currents and with preferences for nocturnal habits. The aim of this study was to analyze the population structure of R. frenatus. The fish were collected in streams of the Itatinga River Basin using electric fishing and, in the laboratory, the individuals were measured, weighed, and dissected. The sex ratio was calculated by the X² test, the weight-length relationship was obtained through a regression and the hypothesis that females are smaller than males was tested by the t test. A total of 91 individuals with equal sex ratio between the sexes were collected, females were, on average, smaller than males and the condition of negative allometry was observed in the species.