Aqua-toxicological Effects of Water Soluble Fractions (WSF) Of Diesel Fuel On O. Niloticus Fingerlings

Five concentrations of water soluble fraction (WSF) of diesel fuel (1.6 ppm, 3.2ppm, 6.4ppm, 12.3ppm and 19.2ppm) were made. To each of the concentrations of the WSF, ten fingerlings of O. niloticus with an average weight of 3g were incubated for 96hours. The 96hour LC₅₀ was determined (8.08ppm). Histopathological examination of the fish gills following exposure to the LC₅₀ and LC₁₀₀ concentrations of the WSF showed gill elongation and lamellar hyperplasia respectively. There was reduction of dissolved oxygen content (from 7.2 to 4.5 mg/l) caused by diesel that dissolved in water. This was below acceptable levels for the sustenance of aquatic life (i.e. 6.0 - 8.0 mg/L). However, the pH reading was not adversely affected. The result tended to suggest that the death of the fingerlings might be related to the decreased dissolved oxygen content of the water due to the presence of diesel. The structural changes of the gills observed may be an adaptation by the fingerlings to oxygen stress. @JASEM