Effect of Red tilapia (Oreochromis mossambicus x Oreochromis niloticus) on growth and survival of the pacific shrimp (Litopenaeus vannamei) in simultaneous polyculture under marine conditions

In the present investigation, we evaluated if the presence of tilapia affects growth and survival of shrimp during pre-growth and grow-out phases. In both experiments, we used a random-blocks design in a single earth pond (0.75 ha) that was prepared and divided into nine (7 x 30 m) enclosures that were considered to be three blocks of three enclosures each. Each randomly stocked block consisted on Pacific white shrimp Litopenaeus vannamei (30 shrimp/m(2)) and three different densities (0.0, 0.25 and 0.50 fish/m(2)) of red tilapia hybrids (Oreochromis mossambicus x Oreochromis niloticus) to give three different treatments with three replicates. The results from the pre-growth and grow-out experiments followed the same trend. In both cases, we found no significant statistical differences (P>0.05) in the final average weight of the shrimp. However, the experimental blocks had a significant (P<0.05) effect on the mean sample weight of shrimp. Shrimp in blocks B and C were significantly bigger than shrimp from block A (P<0.05). For both experiments, we found no effect of the presence of tilapias on survival or growth of shrimp. Keywords: Tilapia-shrimp polyculture, random block experiment, fish and crustaceans.