Effect of stocking density on water quality, survival, and growth of larvae of the matrinx(a)over-tilde Brycon cephalus (Characidae), in ponds

Experiments were carried out in nine 64 m(2) ponds at CEPTA/IBAMA over a pe riod of 21 days in order to evaluate the effect of stocking density (StD) o n survival and growth of larvae of matrinxa, Brycon cephalus. The larvae we re randomly divided into treatments of 30, 60 and 120 larvae m(2) (three re plicates per treatment) and fed three times a day. Samples of larvae were c ollected at days 0, 7, 14 and 21, and the length, weight, coefficient of va riation 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 range test for me an separation (P < 0.05). The following physicochemical parameters of the w ater were always at satisfactory levels for fish culture throughout the exp eriments: temperature, dissolved oxygen, pH, hardness, total alkalinity, am monia and transparency. Increased StD significantly reduced length and weig ht 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 tha t an increase in StD reduces thr growth and homogeneity but increases the p roduction of B. cephalus larvae. (C) 2000 Elsevier Science B.V. All rights reserved.