Median lethal salinity (mls96 h) of two small indigenous fish species amblypharyngodon mola and pethia ticto from indian sundarban

Abstract

Amblypharyngodon mola and Pethia ticto are small indigenous fish species belonging to family cyprinidae and considered as primary freshwater fish widely distributed in Indian subcontinent including Sundarban region. The 96-h median lethal salinity (MLS96 h) level of these fish was found out by exposing to saline water (0-10 ppt) in direct transfer method. The 96-h median lethal salinity for A. mola was found to be 6.20 ppt with 95% confidence intervals of 4.38-7.09 ppt where as for P. ticto it was 6.12 with 95% confidence intervals of 3.67-7.07 ppt. The Probit showed that at 6.12-6.20 ppt, 50% of the both test species shows sensitivity to salinity that leads to mortality. The regression analysis indicated that the mortality rate is positively correlated with salinity concentration having a regression coefficient close to 1.0 in each case. Various levels of external stress responses were noticed at 8 and 10 ppt salinity. The study suggests that these fish can potentially be used as a candidate species for aquaculture in slight brackishwater areas of Sundarban. However, further studies are required to understand the ecosystem based adaptation processes at higher salinity levels.