Influência de diferentes tipos de sombreamentos em tanques-rede no desempenho de tilápias do Nilo (Oreochromis niloticus) na fase juvenil.

Abstract

The objective of this study was to evaluate the growth of Nile tilápia (Oreochromis niloticus, During the juvenile phase in the interference of light using four types of shaders. The expenment was conducted by the sector of Fish Culture, belonging to the Centre for Agrarian Sciences, Federal University of Paraíba, was developed in the period January 2009 to May 2010. The work was conducted in 16 cages with mesh size of 2mm with a volume of lm3 , the depth average of 1 m, placed in earth pond. The cages were stocked with juvenile Nile tilápia with average imúal weight of 17.59 ± 5.53 g and average total length of 9.63 ± 0.95. Arriving at the site and after acclimation, fish were counted, weighed in batches and stored in tanks at a density of 60 peixes/m2, for a total of 960 fish distributed in 16 tanks. During cultivation, the following variables were analyzed water quality: transparency, dissolved oxygen, pH and temperature. We studied the growth performance: weight gain (WG), relative weight gain, gain in length (CG). The experimental design was completely randomized (CRD), in a split plot design in time (Split Plot in Time), where four treatments (100%, 80%, 70% and 50%) with four replicates each, totaling sixteen plots. The results showed that the physicalchemical parameters of water samples were within acceptable leveis. We observed the best performance index of relative weight gain was observed in treatment 80% and already the treatment of 100% had the worst performance. Water temperature values were similar for ali treatments. The worst relative weight gain (%) was in the treatment of 100% of incoming light (290.20%), although the treatment of 80% was more satisfactory because it had the best relative weight gain (442.29%).