Descriptive analysis of the sperm of three South American catfish species maintained ex situ and the influence of morphology on sperm movement

Abstract

Phractocephalus hemioliopterus, Hemisorubim platyrhynchos, and Zungaro zungaro are native of South American rivers whose population is being threatened by the damming of rivers to build hydroelectric dams, fishing pressure and environmental degradation. Basic information on these species’ reproductive characteristics is necessary to enable production in captivity. The aim of this study was to present descriptive data regarding the sperm parameters of these three species maintained in captivity, the correlations between these parameters, and relevant factors, and how these issues can affect sperm quality. Sperm was collected and diluted in Beltsville Thawing Solution after hormonal induction with carp pituitary extract. The evaluated parameters for Hemisorubim platyrhynchos, Phractocephalus hemioliopterus, and Zungaro zungaro were, respectively: Sperm concentration (×10⁹) was 3.00, 1.77, and 1.40 sperm mL⁻¹; Sperm total length was 93.2, 91.4, and 79.4 μm; Motility rate was 71.8, 73.5, and 61.7%; Normal sperm was 35.5, 38.8, and 30.2%. Describing sperm characteristics is extremely important for the artificial reproduction of fish in captivity, contributing to the knowledge on the reproductive biology of the species. In the present study, we discuss these issues to build the knowledge necessary for sperm characterization of these little-studied species. Our results suggest that the morphological abnormalities can affect motility and sperm movement kinetics.