Frequência alimentar para juvenis de Lophiosilurus alexandri utilizando dieta extrusada

Pacamã Lophiosilurus alexandri is a carnivorous fish that has been drastically reduced due to the pressure in the natural environment. For this reason, it has become a species well studied in several aspects related to production. The present study aimed to evaluate different feeding frequencies for juveniles of L. alexandri. Two experiments were carried out to test feed frequencies: F2 = twice daily; F3 = three times a day; F4 = four times a day; And F5 = five times a day with four replicates each. In experiment 1, juveniles were used with 4.3 ± 0.3 cm stocked tanks of 7 L of volume useful in the density of 2 juveniles/L in a static system, during 29 days. The animals were fed daily with extruded feed with 40% crude protein and 1.7 mm. Biometrics of the animals were performed every 10 days for feeding adjustment. In the experiment 2, 960 animals with 6.17 ± 0.16cm were stored in 30 L tanks in a water re-circulation system at the density of 2 juveniles / L for 45 days. For feed, 2 to 3 mm ration with 40% crude protein was used. Every 15 days, the biometry of the animals was performed to adjust the feeding. In both experiments the water quality remained constant with the temperature in the experiment 1 being in the average of 27.2 ± 0.3°C, pH presented values between 7.7 and 8.1 and ammonia with values lower than 0.5 mg/L, and in the experiment 2 the mean water temperature was 28.2 ± 0.1 °C, pH 7.64 ± 0.02 and the ammonia with values of 0.23 ± 0.26 mg/ L. In experiment 1, the feed frequencies did not affect (p> 0.05) the survival, performance and feed conversion of juveniles. In the experiment 2, the feed frequencies did not affect survival, performance, feed conversion, hepatosomatic index, vicerosomatic index, hematocrit, hemoglobin, leukocytes, and erythrocytes of L. alexandri juveniles, (p> 0.05). However, the final length was higher at F4, intermediate at F5 and F3, and lower at F2 (p <0.05). Plasma protein was lower for F4, intermediate on F5 and F3 and higher on F2 (p <0.05). Glucose and triglyceride presented higher values for F2 (p <0.05). Already, cholesterol was higher for F5 and lower than F3 (p <0.05). Despite the biochemical changes in blood in the animals of experiment 2, the juveniles do not show stress, demonstrating that they are healthy animals. It is concluded that the best feeding frequency for juveniles regardless of their size is from twice a day without impairing the health of the animal and its zootechnical performance.