CONTRIBUTION TO ENERGY TRANSFORMATION BY FISH POPULATIONS IN A SMALL TROPICAL RIVER, NORTH VENEZUELA

1. In the Todasana, a small Venezuelan tropical rainforest stream flowing to the Caribbean Sea, fish were sampled at three contiguous sites: pool, rifle, and raceway for a bioenergetic study. 2. Total energy consumed by all fish populations inhabiting these sites was high: 7.9, 1.4 and 4.9 MJ/m2/yr, and food items calculated in wet weight: 2.3, 0.4 and 1.4 kg/m2/yr, respectively. 3. The utilization of food for growth in a gradient of mean monthly water temperatures of 21.9-25.0-degrees-C was low and inversely correlated with temperature. 4. Respiration expenditures, on the other hand, were high and directly correlated with temperature. 5. Of nine species only one was omnivorous, while the food niches of the others were very narrow.