The present study investigated the reproductive biology of silverside, Atherinella brasiliensis (Quoy & Gaimard, 1825) in a tidal flat of Paranaguá Bay, littoral of Paraná State, Brazil. Fish were captured monthly from November 1998 to October 1999 by the mean of a seine-net. For each individual, total body length, total weight, sex, and gonadal weight were recorded. Gonadal development stages were also defined based on the histological examination of the ovaries and on the visual aspects of the testes. It was defined that the reproductive period of A. brasiliensis extends from June to December, based on he analyses of individual gonadosomatic index (GSI) values distribution in relation to the sampling periods, on the monthly variation of the GSI mean values (Curve of Maturation), both for males and females, and on the monthly variation of the relative frequencies of the female maturation stages. During this period, matured, partially spawned and spent females were found in higher frequencies in comparison to the other months. The sizes at first maturation were defined as 7,61cm and 6,92cm for females and males, respectively.
Histology; reproductive biology; tidal flat
