Acute responses of spotted snakehead (Channa punctata) to salinity stress: A study of a freshwater fish to salinity challenges during intrusion of saline water

A climate driven changes in the coastal region of Bangladesh is saltwater intrusion in freshwater, which may directly affect the fishery production as well as economy and food security. Investigation on effect of different concentration of salinities (0, 5, 10, and 15ppt) on hemato-biochemical parameters, behavioral responses and gill morphology at certain time intervals (1, 6, 12, 24, 36, 48, and 72 h) were observed in a spotted snakehead, Channa punctata. In the present study the biochemical parameter and glucose exposed a significant (p <0.05) changes associated with different exposures at different time intervals. The hematological data of C. punctata revealed significant (p <0.05) decrease in red blood cell (RBC) count. The hemoglobin level in every treatment was lower till 24 h and then it increased up to 48 h but white blood cell (WBC) count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) showed significant (p <0.05) increase compared to the control.  Increase and decrease of hematological indices expressed that fish exposure to different salinities were under stress. Unusual behavioral responses with various pathological signs in gills were also perceived. The results specified that the intrusion of saline water into the freshwater have deleterious effects on the hemato-biochemical parameters including gill morphology and behavior. So, the intrusion of saline water should be controlled to avert the losses.