In Nigeria, fish farmers have traditionally harvested fish by persistently and indiscriminately abusing the use of natural plant piscicides. In particular
Derris elliptica, which contains rotenone which is toxic to fish when it is used in higher concentrations than necessary, causing contamination of fresh water bodies and thereby affecting non target organisms.
Toxicity studies of
Derris Elliptica
root powder were carried out with juveniles of
Clarias Gariepinus
using sublethal concentrations of the root extracts
Derris elliptica in 96 h static bioassay. Estimated numbers of healthy
C. gariepinus juveniles were obtained from artisanal fishermen in Ondo State, Nigeria and were transported to the Federal University of Technology, Akure. The 96 h LC50 of
Derris elliptica to juveniles of
C. gariepinus was observed to be 15.0g/ml. Behavioural activities such as erratic swimming, loss of reflex, hyperventilation, increased surfacing frequency and jerky movements were observed. Values of some haematological parameters of
C. gariepinus juveniles were analysed to determine the influence of
D. elliptica root powder on the test fish. The range values obtained for the Packed Cell Volume (PCV), Haemoglobin (Hb), Erythrocyte (RBC) for
C. gariepinus in higher concentration of
D. elliptica root powder were significantly higher; PCV 40.0% - 45.0%, Hb 12.8 – 14.3g /100ml, RBC count 38.5 – 47.4 x 10
6mm
3 than those obtained for Clarias in lower concentrations :PCV 25.0 – 31.2%, Hb 8.3 – 9.8g/100ml, RBC count 21.6 – 32.96 x 10
6mm
23 respectively. Erythrocyte Sedimentation Rate (ESR) decreased than those obtained at lower concentrations of the powder. Erythrocyte Sedimentation Rate (ESR) decreased with increase in
D. elliptica concentrations. The increase in PCV with increase in
D. elliptica concentration indicated positive absorption of Derris solution by the fish while the increase of haemoglobin concentration (Hb) and Erythrocyte count (RBC) in
C. gariepinus at higher concentration of
D. elliptica may be associated with erythrocytes synthesis.
