W. T. Yasutake
Gary A. Wedemeyer
1978
<p><span>The efficacy of mineral salts, pH, and tetramethylthianine (methylene blue) treatment in reducing the acute toxicity of nitrite to fingerling steelhead trout (</span><i>Salmo gairdneri</i><span>) was determined using a static bioassay system at 10 °C. The acute toxicity (96-h LC50) was reduced by a factor of about 24 for 5-g steelhead and 13 for 10-g fish when the total water hardness was increased from 25 to 300 mg/L (as CaCO</span><sub>3</sub><span>). NaCl or CaCl</span><sub>2</sub><span> additions (0–200 mg/L) reduced toxicity by a factor of up to 3 for NaCl and 50 for CaCl</span><sub>2</sub><span>. Increasing the pH from 6.0 to 8.0 decreased toxicity by a factor of about 8 for the smaller and 3 for the larger fish. Methylene blue at 0.1 or 1.0 mg/L was effective in decreasing acute toxicity. For alleviating methemoglobinemia, removing the fish to freshwater for 48 h was about as effective as 1.0 mg/L methylene blue. Chronic exposure in soft water to 0.03 mg/L NO</span><sub>2</sub><span>-N for 6 mo caused no significant growth reduction, gill histological changes, hematological dyscrasias, or impaired ability of the smolts to adapt to 30‰ seawater and grow for an additional 2 mo. </span><i>Key words</i><span>: nitrite, toxicity, fish, methylene blue, pH, salts, acute toxicity, chronic toxicity</span></p>
application/pdf
10.1139/f78-132
en
NRC Research Press
Prevention and treatment of Nitrite toxicity in juvenile steelhead trout (<i>Salmo gairdneri</i>)
article