Optimizing water additives during live transportation of Pangasius catfish (Pangasianodon hypophthalmus): Effects on water quality, bacterial regrowth, and stress response.

Background: In Bangladesh, Pangasius catfish (Pangasianodon hypophthalmus) is commonly transported live from production sites to retail markets. Poor water quality and bacterial regrowth during transportation pose major challenges for animal welfare and fish quality. Objectives: This study evaluated the effects of some water additives such as salt (NaCl), Electromin Saline (ES), and methylene blue (MB) on water quality parameters, bacterial regrowth, and stress responses of Pangasius catfish during live transportation. Materials and Methods: Two experimental trials were conducted: an on-farm trial under controlled conditions and a field trial during commercial transport. In both the trials, tanks containing live fish were treated with additives individually and in combination, while untreated tanks served as controls. Water temperature, pH, dissolved oxygen, ammonia, viable bacterial counts, and blood glucose were measured. Results: Treated tanks showed improved water quality, reduced ammonia accumulation, and significantly lower bacterial regrowth compared with controls. Blood glucose levels were also reduced in treated fish, indicating reduced physiological stress during transportation. Among the treatments, 2.0 ppt salt, 2.0 ppt ES, and their combinations with MB (1.0 ppm) effectively improved water quality, suppressed bacterial regrowth, and reduced transportation-induced stress during live transportation of Pangasius catfish. Conclusions: Salt and ES at 2.0 ppt, alone or combined with methylene blue, can effectively be used during live fish transportation.