Influence of Temperature, Water Hardness, and Stocking Density on MS-222 Response in Three Species of Fish

Abstract

Three responses of rainbow trout (Salmo gairdneri), common carp (Cyprinus carpio), and fathead minnows (Pimephales promelas) to the anesthetic MS-222 (tricaine methanesulfonate) were identified: induction times to total loss of equilibrium decreased with increasing temperatures; resistance to MS-222 increased with increasing water hardness; and resistance to the drug increased when the density of test fish was increased from 0.3 to 0.9 g/L in rainbow trout, 0.4 to 1.2 g/L in carp, and 0.3 to 0.8 g/L in fathead minnows. Our results and others from the literature suggest that temperature, water hardness, and density of test fish, as well as pH and dissolved oxygen, may have significant interacting effects on the anesthetic properties of MS-222.