Biometria e qualidade de água de alevinos de curimatã em diferentes fotoperíodos

Abstract

This study aimed to analyze the biometrics and water quality of a curimatã crop in different photoperiods. The work was developed at the Serra Talhada Academic Unit (UAST). Three polypropylene boxes were placed inside a wooden structure covered with canvas, to avoid interference from external lighting. Inside each box, 3 tanks with a useful volume of 15 L were placed to carry out the experiment, with a stocking density of 2 animals/L. The lighting conditions were represented with fluorescent lamps of 30 W, which were controlled by analog timers. The treatments were represented by three different light conditions: 0Light (L): 24Dark (D), 12L: 12D (control) and 24L: 0D. Each tank received individual aeration through an air compressor and porous stones. A feed frequency with six daily feeds was adopted, with commercial powdered feed containing 55% crude protein, at a feed rate of 10% of the animals' live weight. The following variables were monitored daily: temperature (T), dissolved oxygen (OD), saturated oxygen (OS), salinity (SAL) and pH. At the end of the experiment, biometrics were performed, with which it was obtained: 1) Final number of individuals; 2) Longitudinal length; 3) Average width and; 4) Final weight. With these data, the growth parameters were obtained: biomass gain (GB, g), specific growth rate (TCR,% .day-1 ), survival (%) and the Fulton condition factor (K). The water quality parameters showed mean values equal to T = 24.3 ° C, OS = 69%, OD = 5.6 mg/L and pH = 7.7-7.8 for temperature, saturated oxygen, dissolved oxygen and pH, respectively. The specific growth rates were different, being 0.61, 0.55 and 1.56% for treatments 0L:24D, 12L:12D e 24L:0D. Exposure to photoperiod did not affect the biometric and water quality parameters of fingerlings, but exposure to 24C: 0E significantly improved the specific growth rate (TCE) of the species, which can help in the handling conditions of this fish species.