The objective of this research was to evaluate the effect of natural and artificial diets on the development and behavior of pacu (Piaractus mesopotamicus) larvae, between the 2nd and 10th day post hatch. The larvaes were kept in 30L - plastic boxes (n = 30 boxes), in constant flow-through. The larvae density was 10 post-larvae/L (300 larvae/box). Six diets with 4 sampling days (4, 6, 8 and 10 days post-hatch, n = 30 larvae) using 5 repetitions were tested. The diets were: T1- commercial feed, T2- plancton, T3- artemia, T4- plancton + feed, T5- artemia + feed and T6- artemia + plancton. Larvaes were fed 6 times a day: 4, 8, 12, 16, 20 and 24 hours. The water temperature was kept constant at 27ºC, dissolved oxigen was kept between 6.16 ± 0.34 and pH between 7,16 ± 0,22. At the end of the experiment (10th day post-hatch), the larvaes that received diet containing artemia + plancton (T6) were longer (8.35 mm) and heavier (3518 µg body weight), compared to the larvae fed with the other tested diets. The larvae should be in the laboratory for 6 days after hatch, being feed from the 3rd day after hatch. Before the 6th day, the larvae have the gas bladder completely full and swim continuously.
fish; larviculture; aquaculture; diet