HISTOPATHOLOGICAL EFFECTS OF A PYRETHROID MIXTURE ON THE FINGERLINGS OF Clarias gariepinus (BURCHELL, 1822)

Abstract

The toxic effects of a commonly sold pyrethroid insecticide on Clarias gariepinus fingerling were assessed. One hundred
and sixty fingerlings of mean weight and length, 2.620 ± 0.370g and 6.480 ± 0.598cm respectively were procured,
acclimatized for seven days and randomly allocated to five exposure concentrations of 0.0045, 0.0085, 0.0110, 0.0125 and
0.015ml/L in triplicates, and a control (0ml/L) for 96hours in the laboratory using Completely Randomized Design. The
gills, muscles, intestines and brain were excised for histopathological examination. Some physicochemical parameters of
the test media were determined. Mortalities per exposure concentration were recorded 24hourly, and the 96hr-LC of the
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pyrethroid mixture was calculated using Probit analysis. The results showed that, the mean values of the physicochemical
parameters varied significantly (P< 0.05) and were concentration dependent. The histopathology of the tissues reflected
concentration- dependent degenerations and alterations. Fish mortality varied with time, mortalities were 6.67, 10.0,
56.67, 30.0 and 63.33% in the 0.0045, 0.0085, 0.0110, 0.0125 and 0.015ml/L concentrations respectively, indicating
concentration-dependent effects. The lethal concentration (96hr-LC ) of the toxicant was 0.0128ml/L which implied that,
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the insecticide was highly toxic, and will pose risk to fish and aquatic life by extension if introduced into aquatic
ecosystems. These findings underscore the importance of understanding the toxicological effects of such insecticides on
non-target species, so as to develop effective environmental management strategies to mitigate their ecological risks