Anaesthetic effects of potassium permanganate on Heterobranchus bidorsalis

Heterobranchus bidorsalis fingerlings were exposed to the concentration of 0.10, 0.15,0.20,0.25 and 0.30 g/l of potassium permanganate in replicates. The anaesthesia and recovery rates were studied. The 24 hours LC50 of H. bidorsalis fingerlings exposed to potassium permanganate was 0.20g/1. The effects of potassium permanganate increased with increase in concentrations and duration of exposure to certain extent, the anaesthetic time linearly decreased as the concentrations and temperature increased while the recovery time increased from 1- 5min as concentrations increased. The effects of potassium permanganate was reflected in the fish swimming pattern, rapid opercula movements, hyperactivities, surfacing and leisions during exposure for 24 hours. pH, temperature, dissolved oxygen concentration, salinity and conductivity of the test media showed slight increases. Potassium permanganate is a potent anaesthetic for H. bidorsalis and most effective at the concentrations of 0.10-0.20g/l.