Daily ration levels for nile tilapia (oreochromis niloticus, l.) fingerlings cultivated in low temperatures

Abstract

The experiment was carried out in the Aquaculture Laboratory from the State University of Maringá, with the purpose of evaluating the Nile tilapia fingerlings ideal ration levels. Eighty fingerlings were used, with initial average weight of 0.88 ± 0.12 g and initial average length of 3.76 ± 0.20 cm, divided in 16 net cages distributed in four water tanks (1000L), with five fish each. The design was completely randomized with four treatments and four replications (4, 7, 10 and 13% of the fish biomass). They were fed with a diet of 30% gross protein. The evaluated variables were, final average weight (FW), weight gain (WG), food conversion (FC), final average length (FL), size variation weight (SW) and survival (S). The FW, FL and FC presented positive linear relation (P<0,05). The WG presented quadratic relation (p<0,04) reaching its highest level at 11.55%. The SW and S did not show significant differences (P<0,05) between the treatments. Physical and chemical parameters remained within the appropriate limits for the fish. It may be concluded that the ideal ration level for fingerlings at an average temperature of 23°C is 11.55% of the fish biomass.