INTERAÇÃO DA ALCALINIDADE E DENSIDADE DE ESTOCAGEM EM JUVENIS DE JUNDIÁ Rhamdia quelen (HEPTAPTERIDAE) / INTERACTION OF ALCALINITY AND STOCKING DENSITY FOR SILVER CATFISH Rhamdia quelen JUVENILES (HEPTAPTERIDAE)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

To evaluate interaction of water alkalinity and stocking density on body ionic levels, survival, growth and behavior of silver catfish, Rhamdia quelen, juveniles, a short-term experiment (96 h) analyzed the effect of three alkalinity levels (30, 80 and 130 mg/L CaCO3) and four stocking densities (4, 8, 16, and 24 g/L). In addition, a growth experiment of 30 days verified the effect of three stocking densities (4, 8, 16 g/L) and the same alkalinity levels. Survival and body ionic levels were not significantly affected in the short-term experiment, but after 30 days survival was significantly reduced in the group maintained at the stocking density of 16 g/L and 30 mg/L CaCO3. However, this treatment provided higher weight and specific growth rate compared to the treatment with the highest alkalinity and the same stocking density. The time of capture of the food, in both experiments, was faster in the treatments of high stocking density. In the short-term experiment fish remained mainly in the bottom, and the reduction of stocking density increased swimming speed. The color of the animals was significantly clearer in the lowest densities of the growth experiment. Agonistic side behaviors prevailed in the lowest alkalinities of the stocking density of 8 g/L, and cannibalism occurred only in the stocking density of 8 g/L and alkalinity of 130 mg/L CaCO3 of the growth experiment. The stocking density of 16 g/L and alkalinity of 80 mg/L CaCO3 seems to be the most appropriate for silver catfish juveniles growth in these experimental conditions.

ASSUNTO(S)

estresse social bicarbonato de sódio biologia geral qualidade da água sodium bicarbonate, social stress, water quality

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