Effect of salinity and feeding frequency on the intestinal epithelium and biomass of severum (Heros severus) post-larvae (Heckel, 1840), an Amazonian cichlid with potential for ornamental aquaculture

The present study aimed to evaluate the final biomass and average diameter of enterocytes nucleus in the intestinal epithelium of severum post-larvae (Heros severus) fed with Artemia sp. nauplii and given to four different salinities and two feeding frequencies, during a 15-day period. The experiment was performed at the Federal University of Pará in a completely randomized design, in a factorial system, with four different sodium chloride concentrations in the culture water (0, 2, 4, and 6 g/L), and daily feeding with 1,000 Artemia sp. nauplii per post-larvae, divided into two (8:00 am and 5:00 pm) and four (8:00 am, 11:00 am, 2:00 pm and 5:00 pm) times a day, with four replications per treatment. The final biomass was higher in post-larvae kept in salinity from 0 to 4 g/L and lower at a concentration of 6 g/L. Enterocyte nucleus were larger in animals subjected to 2 and 4 g/L treatments, and smaller in 0 and 6 g/L treatments. Feeding frequency did not significantly influence the evaluated animals' final biomass and enterocyte nucleus diameter. The result of the present study indicates that severum post-larvae can be cultured with up to 4/g L of sodium chloride in the water without affecting its final biomass. It is recommended that severum post-larvae be fed twice a day.