Effects of lead on the plasma electrolytes of a freshwater fish, Heteropneustes fossilis

The freshwater catfish, Heteropneustes fossilis, was subjected to 657.6 mg/L (0.8 of 96 h LC50) and 164.4 mg/L (0.2 of 96 h LC50) of lead nitrate for short-term and longterm experiment, respectively. Blood from fish was collected on 24, 48, 72 and 96 h in short term and after 7, 14, 21, and 28 days in long-term experiment. Plasma calcium and phosphate levels were determined at these intervals. After short-term lead exposure, the plasma calcium levels of the fish remained unaffected at 24 h. The levels exhibited a decrease after 48 h which persisted until the end of the experiment (96 h). Following 48 h of lead exposure to the fish, the plasma phosphate levels remained unchanged. The values exhibited a progressive decrease from 72 h onwards. The plasma calcium levels of the fish exposed to lead for 7 days exhibited a decrease. This decrease persisted progressively until the end of the experiment (28 days). The plasma phosphate levels of lead-exposed fish remained unaffected until day 14. The levels decreased progressively from 21 days onwards.