Anaesthetic effects of aqueous crude leaf extract of desert date (Balanites aegyptiaca) on Nile tilapia (Oreochromis niloticus) fingerlings

Abstract

Desert date (Balanites aegyptiaca) is an evergreen plant which is readily available, inexpensive, and non toxic to human. The leaves contain, among other phytochemicals, flavonoids and alkanoids as active ingredients that could be responsible for sedating or anaesthetizing fish. Many expensive, unavailable chemical and plant anaesthetics toxic to human have been reported but there is paucity of information on anaesthetic potentials of B. aegyptiaca on fish. This study is aimed at determining the anaesthetic potency of leaf extract of B. aegyptiaca on Oreochromis niloticus fingerlings. A total of 120 O. niloticus fingerlings (mean weight 23.13±2.43g and mean total length 12.51±0.39cm) were exposed to 4.00, 3.50, 3.00, 2.50, and 2.00g/L of aqueous crude leaf extract of B. aegyptiaca in 12 rectangular glass tanks (40x25x23cm) filled with 10L each of dechlorinated municipal tap water. Tank with 0.00mg/L had no plant material and served as control. Exactly ten (10) O. niloticus fingerlings were introduced into each treatment and control Tanks which were arranged in randomized block design each with replicate. Anaesthetized fish showed decreased induction time with increase in concentration of the plant extract while recovery time increased with increase in concentration of the extract. The best anaesthesia induction dose was 2.50g/L with mean induction and recovery times of 12.15±0.12 and 11.32±1.18 min respectively. Opercula ventilation rate per minute (OVR/min) decreased with increase in concentration of the plant extract. Induction time and OVR/min were significantly different (P