Bacteriological quality of freshwater fish caught from two natural lakes in the rainforest region of South-Eastern Nigeria

Abstract

The study evaluated the bacteria quality of freshwater fish caught from Oguta and Agulu Lakes. A total of 24 fish samples consisting of 12 samples from each Lake were sampled for four months. The fish samples were transported to the laboratory, processed and compared. Using a sterile scapel and a pair of sterile scissors, section of fish scales, gills, gut, skin, liver, intestine and gonads were removed and subjected for bacteriological analysis. A total of eight (8) bacteria isolates were  identified from the fish samples. The bacterial isolates were Escherichia coli, Aerobic mesophlic bacteria, Salmonella typhi, Listera monocytogen, Vibrio cholerae, Coliforms and Staphylococcus aureus. The gill yielded the maximum isolation rate of 4310(22.3%) of the total bacteria isolates from fish of Oguta Lake, while scale had the maximum isolation rate of  2530(27.1%) of the total isolates from fish of Agulu Lake. The common isolates namely Escherichia coli, Salmonella typhi and Coliforms of the family Enterobacteriaceae formed 79.9% of the total bacteria isolates from Oguta Lake fish and 74.1% from Agulu Lake fish. Staphylococcus aureus was insignificant in Oguta Lake fish (19, 0.1%) but was prominent in Agulu Lake fish where it contributed 150 (1.6%) of the total isolates. Of all the bacteria species identified, only Escherichia coli was isolated from the body parts of fish of both Lakes. Aerobic mesophilic bacteria and Staphylococcus aureus were encountered only in the scales and gut of fish of both Lakes. Salmonella typhi occurred only in the scale of Oguta fish. Vibrio parahaemolyticus was recorded only in the gonads of fish of Oguta Lake and in the intestinal parts of fish of Agulu Lake. The study revealed that the fish from both Lakes is of poor quality and this has a serious health implication. Therefore, sewage should be properly treated before disposal into aquatic ecosystems. Fish should be harvested with unpolluted water as well as handled with caution at post harvest.

Keywords: Bacteria, Freshwater, Fish, Lakes, Public health, Oguta, Agulu, Rainforest, Nigeria