Gonadal development and reproductive period of the characin Astyanax aff. bimaculatus (Characiformes: Characidae) in a tropical reservoir in southeastern Brazil

By

Araújo, Francisco Gerson de
Nascimento, Aparecida A.
Gomes, Iracema David
Sales, Armando
De Oliveira, Beatriz A. Chagas

Type

Article

Date of Publication

2019-10-30

Original Publication

Nature conservation

Volume

36

Pages

1--14

Subjects

freshwater fish , Histology , oocyte , spawning type , spermatocyte

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers 2012-

Identifiers

DOI: https://doi.org/10.3897/zoologia.36.e30610

 

Abstract

The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering and reaching larger sizes than males. The following stages of oogenic cell development were identified for females: primary growth, pre-vitellogenic (cortical alveolar) and vitellogenic. In males, the following stages were determined: spermatogonia primary and secondary, spermatocyte primary and secondary, spermatid and spermatozoa. The spawning occurs most of the year, peaking in January-February, as indicated by the gonadosomatic index. In the peak of the spawning period, the condition factor and hepatosomatic indices decreased suggesting use of stored body energy reserves during the reproduction. Spawning in batches, small-sized oocytes and a long reproductive season suggest that Astyanax aff. bimaculatus fits to an opportunist strategy. Such strategy may facilitate the use of a wide range of lentic and lotic body waters in the Neotropical region.