The effect of water alkalinity on growth and survival of "curimbatá†larvae, Prochilodus lineatus (Characiformes, Prochilodontidae) in laboratory

Abstract

In this work it was tried to verify the influence of different water alkalinity levels on the Prochilodus lineatus larvae survival and growth. The laboratory experiment consisted of three treatments whose medium values of alkalinity were: A í  15.76 mg CaCO₃/L; B í  32.37 mg CaCO₃/L and C í  55.28 mg CaCO₃/L. The maximum and minimum values of temperature, alkalinity, hardness, calcium, magnesium, pH and conductivity were monitored. The experiment was carried out in the laboratory during 42 days, and was divided into 3 treatments, each one with 18 repetitions. The growth curves in total length and dry weight, the dry weight total length relationship, the relative condition factor and the larvae survival rate for each treatment were determined. The growth in total length and dry weight showed significant differences between treatments, being the treatment B, that which permitted the best performance, whereas treatments A and C were similar. The values of survival for the larvae from the three treatments were similar. Curimbatá larvae maintenance in medium values of alkalinity of 32.37±3.73 mg CaCO₃/L, and calcium of 15.73±1.23 mg Ca⁺²/L (treatment B) are therefore recommended, for it provides better growth performance, expressed by total length and dry weight.