Safe pre-release disease treatment with formalin for fall chinook salmon smolts

Standard formalin treatment (167 μL/L for 1 h) applied to presmolts and smolts of fall chinook salmon (Oncorhynchus tshawytscha) 80, 62, 52, 38, 24, and 10 d prior to seawater exposure did not affect freshwater growth or survival during a 20-d period in seawater. There was no consistent effect of treatment on gill Na⁺, K⁺ -ATPase activity.