Intensive nature of aquaculture have subjected farmed fish to a number of stressors due to handling proceedures and transportation from hatcheries to final stages. These stressors have most often been responsible for high mortalities recorded, hence hindering the growth of fish farming. Anaesthetics are used in aquaculture, fisheries and biological researches, as a way to minimize hypermotility during handling and transportation to reduce stress and mortality. Previous studies have reported the use of some plant materials to anaesthetized various fish species including C. gariepinus This studies aimed to investigates the efficacy of Ocimum gratissimum as anaethetic and determine its effects on some haematological parameters of C. gariepinus juveniles.
Fresh leafs of O. gratissimum were obtained from within the university campus, identified, air dry for 5 days and blended to powder. The experimental treatment were prepared from a stock solution of 2g in 10 litres of water (200mg/l) into five concentrations (0, 50, 100, 150 and 200mg/l) in 20 litres of water. Stages of induction and recovery were monitored and recorded using a stop watch. Blood was ollected by severing the caudal peduncle into Ethylene Diamine Tetra acetic Acids (EDTA) for the analysis of various hemaetological parameters using standard methods.
The result revealed that O. gratissimum caused anaesthesia which was concentration dependent. Induction time (min) reduced with increase in concentration while recovery increases as induction time reduces (Table 1 and Figure 1).
Haematological parameters showed some slight changes exspecially at higher concentration however some were not significant (p> 0.05). the mean values of red blood cells, haemoglobin, pack cell volume, mean cell haemoglobin, mean cell haemoglobin concentration, basophile, eosinophile and neutrphile were decreasing with increased concentration of clove powder. Others such as white blood cells, platelets and lymphocytes increased with concentration (Tables 2 and 3). Fish exposed to 150mg/l cause induction shows that RBC, Hb and PCV were not significantly (P > 0.05) from those exposed to 50mg/l which were however not different from the control (0.0mg/).
The observed behavioural changes including initial hypermotility, hyperventilation, loss of equilibrium and no reaction to handling suggest the fish were immobilised (anaesthetized) by the plant material. This was in line with the reports of several researchers who used anaesthetics on fish during handling and transportation Slight changes in the haematological parameters reported in this study corroborates with the studies of many other researchers who have use plant materials as anaesthetic Minimal changes in RBC, Hb and PCV recorded on fish exposed to 150mg/l which were not different (P > 0.05) from the control but induces anaesthesia in 6.22 mins shows it is an ideal concentration. However, researchers have reported a 48 hours reversal to the haematological paramters of fish exposed to clove powder. Further research will be required to investigate the effects of Ocimum of the biochemical paramters of C. gariepinus.