Abstract:
Aqueous and ethanolic extracts of Datura stramonium were conducted to determine their anaesthetic effects on Heterobranchus bidorsalis (20.5+ 0.86g) after exposing the test fish to different concentrations of D. stramonium (1.0, 2.0, 3.0, 4.0 and 5.0ml/l) under America standard bio-essays procedure. The LC10 was determining at the end of the 72 hour exposure. The test fish showed increased hyperactivities; loss of reflex and hyper-ventilation during the exposure to higher concentration of D. stramonium extracts (3.0 - 5.0ml/l). Increase in concentration of D. stramonium of the treatments decreasing the induction time and increase the recovery time, there were significant difference in temperature, pH and dissolved oxygen (P<0.05). H. bidorsalis responses to D. stramonium showed LC10 of safe level of 4ml/l (100/0 died after 24 hours) for ethanolic and 200/0 for 5ml/l aqueous extracts were determined and the test fish recovered after 10 minutes from anaesthetization solution, these time is enough to perform most routine handling procedure like retrieving gametes, length weight measurement, tagging and sex determination. There were significant difference (P<0.01) between aqueous and ethanolic extract and significant correlation in concentration to induction time for aqueous extracts (r = -0.994, P<0.01) and for ethanolic extracts (r = -0.988, P<0.01). Also significant correlation between concentration and recovery time for aqueous extracts (r = -0.990, P<0.01) and (r = -0.992; P< 0.01) for ethanolic extracts. Thus ethanolic extracts of D. stramonium is more effective than aqueous extracts, therefore ethanolic extracts of D. stramonium is recommended over aqueous extracts as anaesthesia for fish at the concentration 0.5ml/l, 1.0ml/l, 2.0ml/l and 3.0ml/l.
