Efeito da restrição alimentar sobre o desempenho zootécnico e composição centesimal de juvenis de lambaris Astyanax lacustris (Lütken, 1875) cultivados em diferentes densidades de estocagem

Abstract

Lambaris are freshwater fish belonging to the genus Astyanax, which comprises the largest group in number of species in the Characiformes order. The species of this genus are small-sized, omnivorous, and have great economic importance. A total of 567 juveniles of Astyanax lacustris weighing between 0.5 and 0.8 g (0.65±0.9g) were randomly selected for this experiment. The study was conducted using polyethylene tanks with 30 L of usable volume, placed in an open system with constant oxygenation and natural light. A bifactorial experimental design was used, with the first factor being stocking density, with three levels 0,5, 0,7 e 0,9 juvenis L-1. The second factor was the feeding restriction, with three levels, feeding every day, feeding five days followed by two days without feeding, and feeding four days followed by three days without feeding. During the experiment, the temperature varied between 26.5°C in the morning and 27.5°C in the afternoon, the dissolved oxygen varied from 4.45 to 12.65 mg L-1, the pH varied between 6.1 in the morning and 8.09 in the afternoon, the total alkalinity varied between 17.9 to 53.7 mg L-1 of CaCO3. The nitrogenous compounds, toxic ammonia and nitrite, averaged was 0.53 and 0.39 mg L-1, respectively. At the end of the experimental period, we observed an average survival of 74.17% and average weight gain of approximately 0.39 g, with no significant differences detected when isolated or combined effect of the factors were evaluated. The average final weight showed values between 1.04 and 1.51 g and the specific growth rate between 0.82 and 1.40 %.day-1. The total biomass and productivity presented average values ranging from 12.11 to 25.66 g and 0.40 to 0.86 g.L-1, respectively. The centesimal composition variables did not present significant differences among treatments. Therefore, the increase in stocking density in the culture of lambaris and short periods of food restriction demonstrate a beneficial relationship for the lambariculture, not compromising the survival and water quality parameters of the culture.