Osmoregulation in piava juveniles, Leporinus obtusidens (Characiformes: Anastomidae), during the exchanges from the water’s pH.

Abstract

The piava is a specie that uses well to the advantage the proteins in vegetables and animals and shows a good performance and it accepts artificial diets, contribute for the fish culture grows up. For the success in the intensive aquiculture it’s important to keep the water quality controlling and analyzing its aspects physicist-chemistry, guaranteeing in this way a growing up culture in the business species from the sweet water, so this research has the objective to check the alterations in the piava’s ionic flow, Leporinus obtusidens, in the water’s pH change, keeping in a closed movement system. The juveniles were displayed in treatments that involved exchanges from pH 5,5; 7,5; 9,0, and for each treatment was verified the ionic variation in eight samples. In a period of three hours of exposition, it happened more ion losses than profits, except for Na+ in pH 5.5. For CI־ that happened a reduction all the exchanges, with the important difference only during the transformation from 5.5 to 9.0 comparing from 9.0 to 5.5. Values in the ionic losses were demonstrated in the pH 9.0 to 7,5 reduction to K+, because of the stress growing up. In this general way, water exchanges, involving pH changes the general stress in the short time period.