Temperature and food availability alters the physiology and aerobic capacity of tambaqui (Colossoma macropomum).

Fish of the Amazon experience both daily and seasonal variation in temperature and food availability. In the present work, we investigated the influence of nutrient status changes resulting from feeding Colossoma macropomum five flooded forest fruits on aerobic and swimming performance. To assess the effects of diet, three groups of fish were provided different types of food. One group of was provided with commercial feed, another was given fruit feed, and the last group was not fed. The effects of temperature were tested by keeping half of each group of animals at either 26 °C or 33°C for 30 days. After this period, the animals were transferred to either a respiratory chamber or swimming tunnel. Then, tissues were collected for relevant analyses. Results showed that C. macropomum depresses aerobic metabolism when food is withheld (27% reduction in ṀO 2), and observed effects were intensified at the highest temperature (40% reduction in ṀO 2 at 33 °C). Further, increased temperature negatively influenced hematological (Ht, Hb, VCM), biochemical (glucose, triglycerides, cholesterol), hepatossomatic index and enzymatic (MDH and CS in white muscle) parameters. The animals feeding commercial and fruits enriched diets, have a physiological and biological advantage when compared to the unfed animals at both temperatures. Metabolic suppression is an important strategy for maintaining swimming capacity in C. macropomum. It is suggested that even after a long period of fasting, carbohydrates are important energetic substrates. Unlabelled Image • Colossoma macropomum reduces oxygen consumption when subjected to prolonged fasting and augments it at higher temperatures. • The group feeding fruit enriched diet has physiological advantages over animals deprived of food at both tested temperatures. • Metabolic suppression and lactate recycling are important strategies for maintaining the swimming capacity of Colossoma macropomum. • Even after a long fasting period, carbohydrates still represent a valuable energy substrate compared to others for Colossoma macropomum. [ABSTRACT FROM AUTHOR]