Evaluation of Anaesthetic Efficacy of Ocimum gratissimum on Clarias gariepinus Fingerlings during Transport

Abstract

High fish mortality caused by stressors during transportation hurts the aquaculture sector specifically fish farmers. Synthetic anaesthetics made from chemical materials are banned because of safety and residual effects. This study was conducted to determine the effectiveness of Ocimum gratissimum (Scent leaf) powder as a natural anaesthetic in transporting C. gariepinus fingerlings. A total of 300 C. gariepinus fingerlings were exposed to 0.00, 10.00, 20.00, and 30.00 g/6L inclusion levels of O. gratissimum leaf powder in 12 gelcans (10litres) filled with 6L of water each. Twenty-five C. gariepinus fingerlings were introduced into each treatment and control in a complete randomized design (four trts and three replicates). The experimental fish were transported from Minna to Suleja at 204 km/h (to and fro). Anaesthetized fish exhibit decreased induction time with an increase in concentration of the O. gratissimum powder while recovery time increased with an increase in concentration. The longest induction and shortest recovery times were recorded in 10 g/6l (T2), while the shortest induction and longest recovery times was recorded in 30 g/6l (T4). The survival rate of fingerlings decreased with an increase in the concentration of the O. gratissimum. A high mortality rate was recorded in trt 4 (30 g/6l) due to increased concentration of experimental plants. The result obtained from the analysis of physical and chemical characteristics of water before, during, and after the transportation showed variation in most of the parameters. There was a significant difference (p<0.05) in dissolved oxygen, pH, and sulphate but no significant difference (p>0.05) was observed in Temperature and Ammonia. Due to its effectiveness and availability; O. gratissimum is close to an ideal anesthetic for use in aquaculture. Farmers could therefore use 10.00 g/6L concentration of the powder for transportation of C. gariepinus.