Egg incubation and larval rearing of piava, Leporinus obtusidens: effect of pH

Abstract

The aim of this study was to evaluate the effect of the pH of the water during Leporinus obtusidens egg incubation and larval rearing. During incubation of the eggs, pH 5.0, 7.0 and 9.0 were tested, being pH 7.0 produced the best results for fertilization rate, hatching, and weight of hatched larvae (29.62 ± 6.01%, 23.57 ± 2.81% and 0.63 ± 0.01 mg respectively). As pH 5.0 caused total mortality of eggs, the pH range was expanded in larval rearing that used pH 5.0, 6.0, 7.0, 8.0 and 9.0, observing that pH 5.0 and 6.0 were lethal to the larvae at 24 and 72 h respectively. At pH 9.0, higher survival (87.22 ± 3.47%) and final weight (3.82 ± 0.19 mg) were registered, whereas the final length of the larvae was the same (P>0.05) for pH 7.0, 8.0, and 9.0. Incubation at extreme pH values was harmful to the development of L. obtusidens eggs, while, at neutral pH (7.0), the best hatching rate and weight of hatched larvae were obtained. During larval rearing, the acidic pH was lethal to the larvae within just a few hours of exposure, whereas higher larvae survival and final weight were registered at pH 9.0.