The gastric evacuation rate is an important variable to measure the daily ration and feeding rhythm therefore, the predation pressure of a piscivorous fish. The evacuation can be influenced by temperature, predator size and food type. In this paper it is presented experimental data of the effect of three food types in Pygocentrus nattereri, a main piscivorous amazonian fish. The temperature ranged from 27 to 31°C and three food items were used (fish muscle, fish fin rays and insect). These food items are ordinarily consumed by the piranha. Predator size had no effect on gastric evacuation. Fish muscles were evacuated at rate of 18.3% h -1, while fish fin and insect average ratio 10.7% h -1. The gastric evacuation increased with temperature. The effect of temperature was more pronounced on fish muscle than in fish fin or insect.
gastric evacuation; fish; Pygocentrus nattereri ; temperature; Amazon