A strain of salinity-tolerant striped catfish (Pangasianodon hypophthalmus) (fingerling size;
15.5±0.09 g each) was used for this experiment. The effects of combined acidic sulfate water and
salinity on fish growth performance, survival rate, and digestive enzyme activities were assessed.
Selected fish were allocated in a completely randomized design with triplicates of nine treatments,
including three pH levels (5.5, 6.5 and 7.5) combined with three salinity levels (3, 6 and 9‰). The
results indicate that there was an interaction effect of pH and salinity on the growth parameters, survival
and feed conversion ratio (FCR) of fish after 60 days of culture (p < 0.05). Fish in the treatment with pH
6.5 and 3‰ salinity presented the highest weight (52.1±0.56 g), while the lowest weight was observed
in the treatment with pH 5.5 and 9‰ salinity. Similarly, daily weight gain (DWG) and specific growth
rate (SGR) were highest in the pH 6.5 and 3‰ salinity treatment (p < 0.05). There were significant
differences among all treatments (p < 0.05) regarding FCR. The lowest and highest FCR values were in
the treatments with pH 6.5 and 3‰ salinity (1.04) and pH 5.5 and 9‰ salinity (1.8), respectively. Fish
in the treatment of pH 5.5 and 9‰ salinity showed very low survival rates when compared to other
treatments. The results suggest that acidic sulfate water with a slightly low pH (pH 6.5) and salinity of
3‰ could be considered a suitable environment for salinity-tolerant striped catfish. Moreover, our
results confirm that a slightly acidic sulfate water environment with a pH of 6.5 is good for catfish
culture.