Mobilization of energetic substrates in the endangered catfish Steindachneridion parahybae (Siluriformes: Pimelodidae): changes in annual reproductive cycle in captivity

Danilo Caneppele,Renato M. Honji,Carlos E. Tolussi,Aline D. Gomes,Renata G. Moreira,Cristiéle da S. Ribeiro

doi:10.1590/1982-0224-20170120

Abstract

ABSTRACT This study aimed at analyzing the energetic substrate (ES) in the main storage tissues of Steindachneridion parahybae, throughout the reproductive cycle in captivity. Differently from wild, in captivity, feeding is not interrupted during the reproductive period, the females do not spawn spontaneously, and they are sedentary. Adult females were sampled monthly and based on their histology and gonadosomatic index (GSI), ovaries were classified into: previtellogenic (PRV), vitellogenic (VTG), and regression (REG) stages. Ovaries at the VTG stage showed higher protein and lipids levels than at the PRV stage with a positive correlation between these substrates and the GSI. Muscle was the main source of proteins transferred to the ovaries, according to the negative correlation between these organs. Lipids remained unchanged in the liver, which is an important supplier in vitellogenesis, a pattern that probably occurs due to the continuous feeding. Muscular glycogen levels were higher at the VTG and REG than at the PRV stages. Plasma triglycerides were also higher during REG, while glucose levels were more elevated during the VTG stage. These results suggest that with constant food supply, the pattern of deposition of ES in S. parahybae is different from that described for other wild potamodromous species.

Highlights

Several studies have used energetic substrates in teleosts as a model to evaluate storage dynamics and mobilization in fish life cycle under different conditions
We described the deposition of energetic substrates in the main reserve tissues throughout the reproductive cycle
gonadosomatic index (GSI) was higher in S. parahybae females with fully developed ovaries (VTG stage), whereas the lowest GSI value occurred at the PRV stage, which evidenced that ovaries performed vitellogenesis, even in captivity

Summary

Introduction

Several studies have used energetic substrates in teleosts as a model to evaluate storage dynamics and mobilization in fish life cycle under different conditions. Studies on the improvement of broodstock nutrition show that protein and lipid (including fatty acid) mobilization significantly improves egg and sperm quality and larvae production (Fernández-Palacios et al, 2011; Araújo et al, 2012). Mobilization patterns include the preferential accumulation of energetic substrates among different teleost species These mobilization patterns change according to reproductive conditions and strategies of oocyte development (Soengas et al, 1993; Sheridan, 1994; Cerdá et al, 1995; Schreck et al, 2001; Jerez et al, 2006). Throughout the reproductive cycle, there are seasonal changes in the biochemical composition (water, lipids, glycogen, and proteins) of fish tissues, especially in females, in which the hepatic metabolism is stimulated during vitellogenesis (Lubzens et al, 2010)

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