Stocking density effect on goldfish, <em>Carassius auratus</em> L., 1758 (Osteichthyes, Cyprinidae) fry, during its initial development phases

Abstract

This experiment aimed to evaluate the influence of stocking density on the goldfish, Carassius auratus (Osteichthyes, Cyprinidae) development, during its initial phases. 300 fry (Lt.: 7.00 mm) were distributed in 20 12-liter aquariums. The experimental design was entirely randomized, with four treatments (0.50; 1.00; 1.50 and 2.00 fry/liter) and five replications. Food consisted of Artemia sp nauplii (supplied proportionally to density) and rations with 40% raw protein, given ad libitum. While the biomass per aquarium linear increase (p<0.001) was recorded according to density stocking levels, the total length showed linear decrease (p>0.001). On the other hand, quadract effect (p<0.05) was reported for mean final weight, condition factor (1.52) and batch uniformity (1.26), while survival rate was not affected (p> 0.001) by the different stocking densities. The physical-chemical parameters rates remained at adequate levels for fish culture, although pH values suffered linear decrease (p<0.05) with increasing fry densities. It may be concluded that the stocking density influences the goldfish fry development, reducing growth parameters. However, since the biomass showed higher values with a density of 2.0 fry/liter, the Carassius auratus fry culture can use such density during its initial development phases.