PHYTOCHEMICAL, PROXIMATE AND SEDATIVE PROPERTIES OF HENNA (LAWSONIA INERMIS) ON THE OPERCULA VENTILATION RATE OF TILAPIA ZILLI FINGERLINGS

Abstract

The high cost of conventional anesthetics and the deleterious effects of prevailing chemical sedatives used in aquaculture have justified the search for natural plant alternative that is cosmopolitan, biodegradable, less toxic with short withdrawal period, and economically affordable. The Phytochemical, proximate and sedative properties of the aqueous crude leaf extract of Lawsonia inermis and its effect on the opercula ventilation rate in Tilapia zilli fingerlings were conducted using standard procedures. Mixed sexed fingerlings of T. zilli of mean weight and length of 42.64 ± 0.82 g and 11.14 ± 0.22 cm respectively were randomly distributed in batches of five fish/per experimental tank. The tank with no test material (0.00g/L) served as the control; while, tanks with test materials at concentrations of 1.50, 2.00, 2.50, 3.00 and 3.50g/L served as test tanks. The qualitative phytochemical analyses of L. inermis revealed the presence of varying proportions of alkaloid, tannin, saponins, cardiac glycosides phenolic and resins, while, the proximate composition includes moisture content (33.2%), crude lipid (12.0%), ash (29.9%), crude fibre (21%), crude protein (3.38%) and nitrogen free extracts (0.52%). There was  significant (p<0.05) dose- dependent increase in the induction of sedation and recovery time of T. zilli exposed to L. inermis aqueous crude Leaf extract as well as marked dose-related decrease in the opercula ventilation rate compared to the control group. No mortality was recorded at low concentrations of 1.50-2.50g/L of the plant extract; in contrast with 50 and 100% mortalities in concentrations of 3.00 and 3.50g/L respectively. In conclusion, the present investigation revealed that L. inermis aqueous crude leaf extract seemed to contain diverse phytochemical constituents that caused sedation with adverse consequences on fish opercula ventilation.