Growth performance of Pangasius krempfi reared in different salinities

Abstract

Pangasius krempfi is an euryhaline catfish species with high economical value and has been farming in several locations of the Mekong delta, Vietnam. This study aimed to evaluate (i) the salinity threshold and isosmotic point, and (ii) the effects of different salinity levels (0, 6, 12, 18, 24, 30, and 34‰) on the growth performance of Pangasius krempfi. Fish were reared in a recirculating aquaculture system (RAS) at a stocking density of 35 individuals per tank. The results indicated that the salinity threshold of P. krempfi was 50‰, at which mortality exceeded 50%. The isosmotic point was determined to be 11‰. After 60 days, no significant differences in weight gain were observed among treatments; however, the highest mean body weights were recorded at 6‰ and 30‰ (38.5 g and 40.1 g/fish, respectively). In contrast, fish reared at 6, 24, and 34‰ exhibited greater length growth compared to other treatments, with the highest mean length observed at 30‰ (17.0 cm), which was significantly different (p < 0.05). Feed conversion ratio (FCR) was not significantly affected by salinities. Survival rates were high (>98%) across all treatments, although the coefficient of variation did not differ significantly among treatments, the lowest variability was observed at 6‰. Overall, these findings indicate that P. krempfi possesses a high tolerance to salinity and sustains stable growth across a broad salinity gradient (up to 34‰), highlighting its strong potential for commercial aquaculture in environments ranging from freshwater to saline conditions.