Effects of Salinity on Vegetation Consumption and Growth in Grass Carp

Abstract

Fingerling grass carp (Ctenopharyngodon idella), 90-130 mm long, were fed a satiation diet of duckweed (Lemna minor) at different salinities for a 14-day period. Daily food consumption ranged from 5.8 to 6.4% of body weight in fish held at salinities between 0.1 (fresh water) and 6‰, declined significantly (P < 0.05) to 1.3% at 9‰, and was nil at 12‰. Dietary conversion rates of grass carp were less efficient at 3 and 6‰ salinity than in fresh water. Growth was reduced slightly at salinities of 3 and 6‰ and greatly at 9‰. Consumption, growth, and survival data obtained in this study indicate that grass carp could inhabit brackish water estuaries and salt marshes of salinities up to 9‰.