Acute and chronic toxicity of nitrite to Clarias lazera.
The present study is an attempt to define acute (96 hr) and chronic (6-months) effects of nitrite on two different sizes of juvenile Clarias lazera. Static bioassays on acute toxicity showed median tolerance limit (TLm) for four days of 28 and 32 mg/l NO2-N for the two sizes respectively. Although nitrite is known to cause hypoxia, as a result of oxidation of haemoglobin to methemoglobin, exposure of both sizes to nitrite resulted in a decreased erythrocyte count haemoglobin content and haematocrit values. Fish exposed to nitrite responded physiologically by producing methemoglobin. A decline in serum total protein levels was recorded during acute and chronic exposure of both sizes to nitrite. This was interpreted as a generalized stress response.
D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D001835:Body Weight; D004906:Erythrocyte Count / Q000187:drug effects; D005399:Fishes / Q000502:physiology*; D006400:Hematocrit; D008706:Methemoglobin / Q000378:metabolism; D009573:Nitrites / Q000633:toxicity*; D010858:Pigmentation / Q000187:drug effects; D012119:Respiration / Q000187:drug effects; D013997:Time Factors
D001798:Blood Proteins; D009573:Nitrites; D008706:Methemoglobin