Grass Carp: Effects of Salinity on Survival, Weight Loss, and Muscle Tissue Water Content

Abstract
Fingerling grass carp (Ctenopharyngodon idella), 100-120 mm total length, were exposed to various hypotonic and hypertonic waters to determine tolerance, body weight loss, and muscle tissue water content. After acclimation at 8.0‰, LD50's for 24, 48, and 96 h were of 15.7, 15.1, and 15.1‰ salinity, respectively. No mortalities occurred in fish exposed at 14.0‰ for 96 h; at 12.0 and 14.0‰, decreases of 8.5 and 11.3% in total body weight occurred. At lower salinities, declines in body weight were only 0.8-1.7%. As salinity increased, the water content of muscle tissue declined from 80.0% in fresh water to 74.4% at 14.0‰. Death at salinities higher than 14.0‰ was attributed to the failure of cellular processes to adjust to dehydration.