Survival of Chinook Fry (Oncorhynchus tschawytscha) Following Exposure to Benzalkonium Chloride in Soft Water

Abstract

Abstract Chinook salmon fry (Oncorhynchus tschawytscha) were exposed in fresh water to 1, 2, 3, 4, 5, and 10 mg/L benzalkonium chloride for 1 hour. Although mortalities occurred at 2.0 mg/L, the commonly recommended therapeutic level, no histopathological gill damage was observed until 3.0 mg/L had been reached. At concentrations higher than 3.0 mg/L gill damage was severe, and no fish survived exposure to levels greater than 4.0 mg/L. The results indicate that products containing benzalkonium chloride should not be used to combat gill disease problems among juvenile chinook.