Prerelease disease treatment with potassium permanganate for Fall Chinook salmon smolts

Standard potassium permanganate treatment (2 mg KMnO₄/L freshwater for 1 h on three consecutive days) was applied to presmolts (parr) and smolts of fall chinook salmon (Oncorhynchus tshawytscha). Smoltification was determined by gill Na⁺,K⁺-ATPase activity. Treatments were conducted 73, 59, 45, 31, 16, and 2 d prior to full-strength seawater entry in aquaria. Potassium permanganate did not affect either growth or survival in seawater over 25 d. We observed a delayed rise in gill Na⁺,K⁺-ATPase activity in fish treated 16 d prior to seawater entry.