Growth performance of different strains of Nile tilapia, Oreochromis niloticus, (Linnaeus, 1757) in cages.

The aim of this study was to verify the growth performance of different strains of Nile tilapia, Oreochromis niloticus, in individual cages installed in the laboratory of Universidade Estadual de Londrina (Paraná, Brazil). The strain from Thailand, the local strain of the northern Paraná and their hybrid (Thailand male x local female) were studied. The experiment was carried out in 36 individual cages with controlled water quality and water temperature. The initial weight was 37.20  4.83; 35.05  3.56 and 35.52  4.19g for Thailand, hybrid and local strains respectively. At the end of the experiment the weights were 64.08  12.16; 53.36  10.08 and 52.73  7.92g for the same previous sequence. The condition factor (Kn) estimated for the different strains showed no difference (p>0.05). Primer software was used for variance analysis and for Student Newman Keuls test. The Thailand strain presented the best growth performance (p>0.05), but no significant difference was found between local and hybrid strains.