Salinity tolerance and survival of an Indian major carp, Cirrhinus mrigala (mrigal): Feasibility assessment for rearing in inland saline water

Abstract

An experimental trial was conducted in triplicate to determine the effect of different salinity levels 0 (SA0), 2(SA2), 4(SA4), 6(SA6), 8(SA8) and 10 (SA10) ppt on survival, behaviour, and morphological changes in mrigal, Cirrhinus mrigala fingerlings during short-term rearing in inland saline water in glass aquaria for 10 days. Healthy fingerlings (average length-11.18 cm, average weight-11.05 g) of mrigal, procured from the Instructional cum Research Farm, College of Fisheries, were conditioned for one week at 0 ppt (freshwater) in FRP pools and conditioned fingerlings were gradually acclimated to varying salinities by raising the salinity by 1 ppt hourly and then stocked into glass aquaria of respective salinity levels @ 10 fingerlings aquarium-1. Predetermined salinity levels and the water level were maintained in all the treatments and fish were fed with pelleted feed (crude protein 26.12%) @ 0.5% of fish body weight, once a day, as sustenance ration throughout the experimental period. The results indicated that all the water quality parameters, except temperature, varied significantly (P0.05) across treatments. Furthermore, no fish mortality occurred up to 6 ppt salinity during the experiment. In contrast, survival rates were 93.33% and 86.67% at 8 and 10 ppt salinity, respectively at the termination of the experiment. Normal swimming and feeding (feed intake) behaviour were recorded up to 6 ppt, whereas no adverse morphological changes were observed in fish during the tolerance test in all the treatments. From the above results, it can be concluded that mrigal, C. mrigala can tolerate salinity up to 6 ppt during short term (10 days) rearing in inland saline water.