Comparative Acute Toxicity of Aqueous Extract of Aloe vera (Aloe barbadensis) Leaves and Roots on Fingerlings of African Catfish, Clarias gariepinus (Siluriformes: Clariidae)

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Abstract

The comparative acute toxicity of the aqueous extract of Aloe vera leaves and roots on fingerlings of the African Catfish (Clarias gariepinus) was conducted under static bioassay in the laboratory for 96h to examine and compare the toxic effects of the plant leaves and roots on the fish. Range finding bioassays were conducted to get the range of concentrations for the definitive bioassays. The range of concentrations of test media for the leaves was 0 - 650 mg L-1 while that of the roots was 0 - 980 mg L-1. The median lethal concentrations (LC50) were determined using probit analysis. Ten active experimental organisms of about the same size were randomly placed with scoop net in each of the test medium, each concentration having replicates including untreated media. The 96h LC50 of the leaves against exposed fingerlings was 380.6 mg L-1 with lower and upper confidence limits of 324.3 and 426.1 mg L-1 respectively while that of the roots was 554.7 mg L-1 with lower and upper confidence limits of 509.5 and 606.7 mg L-1 respectively. Paired t-test showed that there was no significant difference (P>0.05) between the test A. vera leaves and roots on the test species. The water quality parameters showed that the leaves caused increased temperature, conductivity, dissolve oxygen, pH, alkalinity, hardness and ammonia while the roots caused an increase in temperature, conductivity, alkalinity, hardness and ammonia and there was a decrease in pH while dissolved oxygen remained the same Based on toxicity ranking, the LC50 of the test plant materials on fingerlings of C. gariepinus indicated that the leaves were found to be moderately more toxic than the roots

Keywords: Acute toxicity, Aloe vera, Aqueous extract, Clarias gariepinus, Static bioassay

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