Larval performance of the freshwater prawn (Macrobrachium rosenbergii De Man, 1879) submitted to different feeding systems

The feeding is one of the most important factors to larval development and the sucess of the commercial cultivation of decapod crustacean larvae depends on the efficient and economic utilization of the available food. The performance of Macrobrachium rosenbergii larva submitted to four different feeding systems was tested by using the daily observation of the larval substages and the first metamorphoses. The larvae were stocked in a density of approximately 100 larvas.l(-1), in 16 tanks, with 33 liters capacity. The experiment was divided in four experimental units (blocks). Four feeding systems were tested in the hatchering in an open circuit, with four replicates for treatment. The feeding systems in which progressive substitutions of the nauplii of Artemia sp. (nas) were accomplished, for the rotifer Brachionus plicatilis (rots), the following treatments were tested: 100% Brachionus plicatilis(30 rots/mL) (T1); 100% Artemia(5 nas/mL) (T2), 60% Artemia(3 nas/mL)+ 40% Brachionus plicatilis (12 rots/mL) (T3) and 40% Artemia (2 nas/mL) + 60% Brachionus plicatilis (18 rots/mL) (T4), Humid ration was added to all treatments. The results of the change of the larval stage demonstrated that there was not significant difference among the treatments T2, T3 and T4. The treatment T1 (100% Brachionus plicatilis) had total mortality in the 14(th) day of the experiment. The effect of the occurrence of the first metamorphoses for post-larvae, ocurred at 27(th) day in the treatments T2, T3 and T4. Consequently, the hatchering cycle to the metamorphosis of 90% for post-larvae (PL1), was the same in the respective treatments (35 days). Therefore, the use of the enriched rotifer and frozen in the feeding systems of the larvae allowed a satisfactory performance in terms of larval development of M. rosenbergii until the passage for the post-larvae stage.