Temperature and Feeding on the Modulation of Ammonia Excretion Rate of Piaussu Leporinus macrocephalus

Abstract

The aim of this study was to evaluate the combined effect of temperature and feeding on ammonia excretion rate in piaussu. Fish (10.3 ± 1.7 g) were acclimated in a RAS and subjected to five different temperatures (15, 19, 23, 27 and 31°C), feeding (twice a day until satiation) and fasting regimens. Nine fish per treatment were individually distributed in tanks and ammonia excretion rate was estimated for up to 24h, at every four hours, for the feeding and fasting treatments. During this period the food consumption was estimated. As expected, the excretion rate of fed animals was generally higher compared to non-fed fish, except for fish maintained at 15°C. Higher temperatures increased excretion from 27°C and forward in fasting treatments. Temperature was directly related to higher food consumption, which in turn was the main responsible for the variability of excretion rate. Postprandial excretion peaks occurred since the first 4 up to 12 h after feeding and were followed by a return to baseline levels after 16 h. Ammonia excretion rate in piaussu is influenced by both temperature and feed, being strongly influenced by the latter. Based on the findings of the present study, the temperature for the rearing of this species should be around 27ºC.