Ammonia excretion at different life stages of silver catfish

Neiva Braun,Luciano De Oliveira Garcia,Bernardo Baldisserotto,Alexssandro Geferson Becker,Vania Lúcia Loro

doi:10.4025/actascianimsci.v34i1.11898

Abstract

This study examined ammonia excretion at different life stages (eggs, larvae and juveniles) in silver catfish (Rhamdia quelen) and determined the influence of fasting time on ammonia excretion. Eggs and larvae were collected from incubators at different times after fecundation and placed in chambers. Juveniles were separated into two weight classes (2-50 g and 150-320 g) and placed in individual chambers after feeding. Water was collected from each chamber to determine ammonia excretion. Ammonia excretion by the eggs was low, but when hatching began approximately 28h after fecundation, excretion increased until 48h after fecundation. In fasting silver catfish juveniles, there was a significant negative correlation between ammonia excretion and weight. Moreover, ammonia excretion decreased significantly after 12 and 48h of fasting (compared to 6h fasting) in the smallest and largest specimens, respectively. Consequently, during incubation of silver catfish eggs, water renovation must be increased at hatching time to avoid a build-up in the concentration of ammonia. In addition, as ammonia excretion in this species increases after feeding, feed must be discontinued when ammonia levels in the tanks are high to avoid a further increase of this metabolite and consequent mortality of silver catfish.

Highlights

Ammonia is the dominant end product of nitrogen metabolism in most teleosts, and is toxic at low concentrations, in NH3 form (CHEW et al, 2006; FELIPO; BUTTERWORTH, 2002; IP et al, 2004; WICKS; RANDALL, 2002)
The main internal source of ammonia in fish is through the catabolism of proteins, and most of this waste product is produced in the liver of fish during the transamination of amino acids followed by the deamination of glutamate (WICKS; RANDALL, 2002)
Ammonia excretion by eggs was low, but when hatching started approximately 28h after fecundation, excretion increased until 48h after fecundation (Figure 1)

Summary

Introduction

Ammonia is the dominant end product of nitrogen metabolism in most teleosts, and is toxic at low concentrations, in NH3 (unionized ammonia) form (CHEW et al, 2006; FELIPO; BUTTERWORTH, 2002; IP et al, 2004; WICKS; RANDALL, 2002). Animal Sciences through the gills (WILKIE, 2002), and teleosts usually increase the excretion of ammonia after feeding (ALTINOK; GRIZZLE, 2004). Ammonia appears to be the dominant end product during the embryonic and yolk sac stage of freshwater teleosts (DABROWSKI et al, 1984; OLIVA-TELES; KAUSHIK, 1990; WRIGHT et al, 1995). Ammonia excretion in Caregonus lavaretus increased during the pre-hatching period, from 52.1 to Maringá, v. Ammonia excretion in Caregonus lavaretus increased during the pre-hatching period, from 52.1 to Maringá, v. 34, n. 1, p. 15-19, Jan.-Mar., 2012

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