Physiological responses in embryo and larvae of striped catfish (Pangasianodon hypophthalmus) exposed to different salinities

Abstract

The experiment was studied on the tolerant physiological parameters of the eggs and larvae of striped catfish groups (selected group, control group, and freshwater group) in different salinities. The research includes two experiments. The first experiment was conducted after the eggs were artificially fertilized. The eggs were incubated in 0, 1.25, 2.5, 3.75, 5, 7, and 10 ppt according to the broodstock groups. The fertilized rate, hatching rate, and osmolality were observed. The larvae incubated in freshwater from different broodstock were used for the second experiment. The larvae were nursed in 20 days in 0, 5, 10, 15, and 20 ppt based on broodstock groups to observe survival rate and measure the osmolality and the ionic concentrations of fish. The results showed that the embryo of the striped catfish can be fertilized and hatched in 10 ppt. The fertilization rate and hatching rate were decreased when salinity rise. The hatching rate of selected group was highest. The survival rate of larvae were also decreased from 0-10 ppt. At 15 and 20 ppt, all of larvae were died after 20 days. The survival rate and growth performance in selected groups was higher than other groups. The osmolality of larvae groups increased with salinity. The osmolality of selected group was the highest at all salinity. Similarly, ion concentration was significantly affected but the differences between fish groups was not remarkable.