Effect of different ration levels for grass carp (Ctenopharyngodon idella v.) fingerlings in experimental conditions

Abstract

The experiment was carried out in the Aquaculture Laboratory of State University of Maringá with the objective of evaluating the ideal ration levels for grass carp fingerlings. Eighty fingerlings were used, with initial medium weight of 0.73 ± 0.10 g and initial medium length of 4.4 ± 0.22 cm, divided in 16 net-cages distributed in four ponds (1,000 L), with five fish each. The design was completely randomized with four treatments and four replications (1, 3, 5 and 7% of the fish biomass). The evaluated parameters were final mean weight (FW), weight gain (WG), feed conversion (FC), final mean length (FL), uniformity (UNI) and survival (S). The (FC) and (WG) presented quadratic relation (P<0.05), with maximum point 6.17 and 6.0%, respectively. The (FL) exhibited positive linear relation (P<0.05) when the ration level increased. The (UNI) and (S) did not reveal significant differences (P>0.05) between the treatments. Physical and chemical parameters remained within appropriate limits. It was possible to conclude that ration distribution in a proportion of 6.0% of the fish biomass for grass carp fingerlings is appropriate to a better development and survival in an average temperature of 26°C.