K.S. TILAK, K. VEERAIAH AND V. JANARDHANA REDDY
Abstract
The effect of NitriteNitrogen was tested to the fish Puntius sophore (Hamilton) and Channa punctatus (Bloch). The static and continuous flow through tests were applied for toxicity tests. The LC of static and continues flow through tests for 24 h are 126.4 and 146.2 and 106.00 and 143.7 respectively. The fish Puntius sophore and Channa punctatus are exposed to lethal and sublethal concentrations of NitriteN for seven days. The percentage of methemoglobin slowly increased in the first three days (23, 31 and 40 in Puntius and 22, 40, 50 in Channa). From the fourth day onwards the percentage of methemoglobin is more or less constant (50-60 in both fishes). The percent of functional haemoglobin decrease correlates with the demand for more oxygen and degree of damage in gill tissue.