||Acute Toxicity of Ammonia and Nitrite to Cutthroat Trout Fry.
Thurston, Robert V. ;
Russo, Rosemarie C. ;
Smith, Charlie E. ;
||Montana State Univ., Bozeman. Fisheries Bioassay Lab.;Environmental Research Lab.-Duluth, Monticello, MN.
Lethal dosage ;
Cutthroat trout ;
Salmo clarki ;
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The toxicity of ammonia and of nitrite was tested on cutthroat trout (Salmo clarki) fry (1-3 g) for periods up to a month in eight laboratory flow-through bioassays. Median lethal concentration (LC50) values for ammonia (mg/liter un-ionized NH3) were 0.5-0.8 for 96 hours, and 0.3-0.6 for 36 days. Nitrite LC50 values (mg/liter NO2-N) were 0.5-0.6 for 96 hours, and 0.4 for 36 days. Tissues of fish exposed for 29 days to 0.34 mg/liter un-ionized ammonia evidenced degenerative changes in gills, kidneys, and livers. Cutthroat trout fry are comparable to rainbow trout (Salmo gairdneri) fry in their susceptibility to acute toxicity from aqueous ammonia and nitrite.