Abstract

The study evaluate the acute toxicity of aqueous extract of Adenium obesum stem bark to determine the median lethal concentration (LC50) in exposed Clarias gariepinus under laboratory conditions using static non-renewal bioassays over a 96-h exposure with continuous aeration. The fish (N=180, mean weight and length 21.48 ± 3.32 g and 11.37 ± 1.23 cm), were randomly distributed 10 (ten) fish per group in triplicates. There were six (6) experimental groups G1 (Control), G2 (6.5 mg/l), G3 (7.8 mg/l), G4 (8.5 mg/l), G5 (9.5 mg/l) and G6 (11.5 mg/l). Exposed fish showed clinical signs of changed behaviors with adaptive responses, respiratory distress and nervous compromise, including mortality in some of the exposed fish. The clinical signs observed and their severity was concentration and exposure period-dependent. The LC 50 value of 8.38 mg/l was established for the extract in the exposed fish where mean mortality was significantly (p<0.05) concentration and exposure period-dependent. The phytochemical constituents and LC 50 of aqueous extract Adenium obesum stem bark evaluated will assist toxicologists and aquatic researchers in determining the safety concentrations of Adenium obesum in exposed Clarias gariepinus juveniles and aquatic studies.

Keywords: Adenium obesum; Clarias gariepinus ; Toxicity; Median Lethal Concentration; Toxicology