Toxicity of mixtures of quinaldine sulfate and MS-222 to fish

Verdel K. Dawson

The acute toxicities of mixtures of two fish anesthetics (quinaldine sulfate, and MS-222) to coho salmon, rainbow trout, brown trout, brook trout, lake trout, carp, channel catfish, bluegill, and largemouth bass of various sizes were determined in 15-, 30-, and 60-minute and 24-, 48-, and 96 hour static toxicity tests. The effects of various temperatures, water hardnesses, and pH's on the mixture's toxicity were evaluated. Temperature changes had little influence on the effect on the drugs. In very soft water, solutions of the combination are acidic and considerably less toxic than in harder water. The toxicity of the mixture decreases with decreasing pH, especially below pH 6.5. Safety indices (lethal concentration / effective concentration) indicate that the safety margin is greater at shorter exposures.