TOXICITY OF AQUEOUS EXTRACT OF Thevetia neriifolia LEAVES TO AFRICAN CATFISH (Clarias gariepinus) JUVENILES

Abstract

Clarias gariepienus juveniles with mean weight of 23.5g±5.0g were put to plastic tanks (15 litres) at 10 fish per treatment in replicates, based on the concentration of Thevetia neriifolia (milk bush) leaves extract administered (3.0g/l, 3.2g/l, 3.4g/l, 3.6g/l and 3.8g/l) respectively. Concentration 0.0 g/l served as control. The different concentrations were administered to the various tanks for four consecutive days. After 96 hours, no mortality was recorded in the control 0.0g/l and 13-83% mortality was recorded in all other concentrations. In concentrations 3.0g/l, 3.2g/l, 3.4g/l, 3.6g/l and 3.8g/l; 13%, 20%, 40%, 57% and 83% mortality were recorded respectively. Clarias gariepinus on exposure to varying concentrations of T. neriifolia leaves extract affected the blood profile as there were significant differences (P<0.05) in all the parameters tested, except for the mean corpuscular haemoglobin which was the same for all the samples. Highest value (6.10±1.00) of the white blood cell was observed in the concentration of 3.4g/l followed by 3.6g/l (5.60±0.92) while the least value (4.90±0.70) of leucocytes was observed in 3.0g/l. Haemoglobin values ranged between 9.05±0.25 and 12.40±0.30. Highest haemoglobin (12.40±0.30) was observed in the control (0.0g/l) which was significantly the same (P<0.05) with Hb of fish exposed to 3.0g/l (11.43±0.96) and 3.2g/l (11.20±0.90). The control (0.0g/l) had the highest RBC counts (4.58±0.45), followed 3.0g/l (4.48±0.45) while the least count (3.38±0.45) of red blood cell was observed in 3.6g/l which was significantly the same (P<0.05) with3.8g/l (3.63±0.42). The PCV (37.0±1.00) was observed in the control (0.0g/l) which was significantly the same with 3.0g/l (36.67±1.00). However the lowest PCV (28.00±4.0) was obtained in fish exposed to 3.4g/l T. neriifolia. The MCH ranged from 81.66±0.85 to 90.58±0.81. Highest value (90.58±0.81) was in 36.g/l which the least was observed in 3.8g/l (81.66±0.85). However, the MCV were significantly the same across the treatment media. Deformation of the gills, cellular infiltration of the liver and deterioration/degeneration of the cells the skin were observed respectively during the histological study. At 96 hours, LC50 was 3.3g/l. Other observations during the experiment include frequent jumping, erratic swimming, patches on the ventral surface of the fish and skin discoloration.