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The research work was to investigate the toxicological effect of wastewater on cat
fish (Clarias gariepinus). Domestic wastewater from different locations in Federal University of
Technology Akure, Nigeria were collected and analysed. The rate of degradation, changes in
physicochemical parameters as well as the microbial isolation was studied using standard methods.
The result showed that all the samples were heavily populated with microorganisms, having an
average microbial load of 1.86 x 107cfu/ml. The coliform was highest in sample from Akindeko
with a microbial load of 1.85 x 107 cfu/ml. A total of sixteen bacteria were identified among which
are Proteus vulgaris, Shigella dysenteriae, Serratia marcenscens and Clostridium botulinum. The
fungal isolates were eight with Aspergillus flavus predominating. The pH values ranging from
7.10 to 9.20. The biochemical oxygen demand (BOD) increased with increased days of degradation.
Result of the toxicological assays showed that waste water caused a reduction in haemotological
parameters such as packed cell volume (PCV) and haemoglobin concentration (HB), while causing
an increased value of the Erythrocytes sedimentation rate (ESR), white blood cell count (WBC),
monocytes, and Eosinophils. The results obtained in these work therefore has shown that wastewater
from the various sources are deleterious to aquatic organisms especially fish. There is therefore
need to ensure adequate treatment of these wastewater before discharging them into water bodies
and the environment and environment respectively.
Keywords: wastewater, physicochemical microbial load, toxicological effect, environment