Abstract

Tank-raised Clarias gariepinus (mean total length, 30.05±4.05cm,SD; mean weights, 250.04±50.22gSD) were injected intra-muscularly with two millilitres per kilogram of each of five concentrations (2.00, 2.00, 6.00, 8.00 and 10.00ppm) of aqueous extracts of leaves of Lepidagathis alopecuroides above the lateral line. The fish in the control group were injected with same dose of distilled water. There were four fish per treatment level. On the 14^th day the fish was assessed for organ indices (hepatosomatic index, HIS; cardiosomatic index, CSI; renatosomatic index, RSI and spleenosomatic index, SSI) and Fulton’s condition, K . Blood samples were analysed for packed cell volume, PCV; haemoglobin, Hb; red blood cell, RBC white blood cell, WBC and platelets. The plasma was analysed for the transaminases (aspartate transaminase, AST; alanine transaminase, AST), alkaline phosphostase, ALP and lactate dehydrogenase, LDH.  The values of PCV (p<0.05), HB and RBC (p>0.05) in the control were higher than those in the treated group. However, the decline was not concentration-dependent. The increase in the number of WBC in the exposed fish was twofold and above (p<0.05) that in the control, 66.67±23.09x10⁶cells/l with highest value (360.00±33.24x10⁶cells/l) recorded at 10.00ppm. The response pattern of platelets to the extracts varied very widely among the treated group (p<0.05) with fish injected with 2.00ppm having the highest value (100.00±33.20x10⁹cells/l), which was about twofold that at other concentrations.  Generally, the activities of AST, ALT, ALP and LDH were inhibited below the control value without any direct relationship to toxicant concentration. Nevertheless, AST generally showed a decline in activity from that of the control except at 4.00ppm (117.75±9.80IU/L); ALP declined with a slight increase at 10.00ppm above the control.  There was no difference (p>0.05) between the organ indices in control and treated group except in the SSI. K and HSI showed variable responses relative to extracts concentration, while the heart showed a very slight decline in size. RSI and SSI had a reverse pattern. Exposure of C. gariepinus to L. alopercuroides in the open waters during fishing activity may impact negatively on the physiology of the fish as manifested in changes in some of the blood parameters, plasma enzymes and organ indices of the fish.

Key words: Clarias gariepinus, Leidagagthis.alopercuroides, plasma enzymes, blood parameters, organ indices, condition.