Effect of stocking density on water quality, survival, and growth of larvae of the matrinxa,

Experiments were carried out in nine 64 m ponds at CEPTArIBAMA over a period of 21 Ž . days in order to evaluate the effect of stocking density StD on survival and growth of larvae of matrinxa, Brycon cephalus. The larvae were randomly divided into treatments of 30, 60 and 120 ̃ 2 Ž . larvae m three replicates per treatment and fed three times a day. Samples of larvae were collected at days 0, 7, 14 and 21, and the length, weight, coefficient of variation of length, and specific growth rate were determined for each sample. Survival, production and food conversion were calculated at day 21. Data were analyzed statistically by ANOVA and Tukey’s multiple Ž . range test for mean separation P-0.05 . The following physicochemical parameters of the water were always at satisfactory levels for fish culture throughout the experiments: temperature, dissolved oxygen, pH, hardness, total alkalinity, ammonia and transparency. Increased StD significantly reduced length and weight from day 7, and increased the coefficient of variation of length on day 21. A correlation between specific growth rate and StD was observed only on day 14, and there was no correlation between StD survival. We conclude that an increase in StD reduces the growth and homogeneity but increases the production of B. cephalus larvae. q 2000 Elsevier Science B.V. All rights reserved.