Bacteria diseases are widespread and can be of particular importance in fish farming. Bacteria exist as micro flora in water until certain environmental conditions such as poor water quality occur, which could impose a stress on fish, thereby making them vulnerable to infection, most especially by pathogenic bacteria. This study was carried out to assess and compare the bacteria diversities and population in Clarias gariepinus, Sarotherodon melanotheron and Oreochromis niloticus, in the three grow out ponds of the aquaculture unit of the Department of Marine Science and Lagoon Front of the University of Lagos. It also aims at determining their public health significance. The experiment was carried out between May-September 2013. Water samples were collected from the three grows out ponds in the Department of Marine Sciences and from Lagos lagoon Front of the University of Lagos. In each case, water samples were analysed for the possible indicator organisms of faecal and industrial pollutions such as Escherichia coli, Staphylococcus aureus, Salmonella spp., feacal streptococcus, Vibrio spp., and Clostridium spp. From the result obtained, all the bacteria listed above were first seen as common bacteria in all the samples of water analysed. Further studies (biochemical tests) also reveal bacteria such as Klebsiella spp., Proteus spp., Enterobacter aerogenes, Citrobacter spp. and Pseudomonas aeroginosa. Moreover, the same indicator bacteria seen in water samples were also detected in the different body parts (flesh, mouth, gill and gut) of each of the fish species analysed, both from the Departmental ponds and Lagoon front, except Clostridium perfringes (C. welchii), Vibrio cholera and Salmonella typii which were found in the gut of those fish species from the departmental ponds A-C and in the mouth, gill and gut of the fishes from lagoon front. The population of each of these bacteria was found to be highest in the gut region, followed by the gill, the mouth and least in the flesh. There was no significant difference in the population of each of the bacterial across pond water (P>0.05). Same is the case with each bacteria analysed across body parts of the fish species (skin, mouth, gill and gut) in the Departmental ponds, that is, no significant difference (P>0.05). But, when compared with the lagoon front (both for water and fish samples) the difference was highly significant (P<0.05). None of the population of the bacteria in the ponds exceeds the limit for human consumption. The bacteria load in the lagoon fish (skin, mouth, gill and gut) was higher than the recommended limit for human consumption. Therefore, they are not fit for consumption most especially samples from the mouth, gill and gut, except effective processing treatment is employed before consumption. Due policy should also be taken by the government to curtail the tradition of indiscriminate discharge of untreated effluent into the lagoon.

The Ilo-Idimu river is situated in the heavily industrialised Ota Town, Ogun State, Nigeria, with industries empting their wastes or part of their wastes into the river. The community use the water of the river for domestic purposes such as cooking, drinking, bathing and washing. Iron (Fe) was the most abundant heavy metal amongst the four [Copper (Cu), Iron (Fe), Zinc (Zn) and Lead (Pb)] heavy metals tested for in the Ilo-Idimu River. Though, the levels of lead was more in the littoral midstream (Lit B) and benthic upstream and downstream (Bent A and C) 1.60, 1.40 and 1.30 mg/l respectively. The fish samples of Sarotherodon galileaus tested for the four heavy metals showed that lead (Pb) was present only in the gut of the fish. For the other heavy metals the trend are Cu > Zn > Fe in the scale, in the flesh of the fish Cu > Fe > Zn, while Fe > Cu > Zn in the gills and gut of the fish. The levels of the heavy metals tested in the water and fish samples were lower than the WHO standards therefore, there is no immediate threat to the biodiversity of the aquatic species in the river and to the health of the community using the water for various domestic uses.

Abstract:Ilo-Idimu River is a tropical zone lying between 60.47ºN of the equator and 20.33ºE, and 30.18ºE of the Greenwich meridian. The aim of this research is to determine the concentration of heavy metals in Sarotherodon galilaeus; a predominant fish species in Ilo-Idimu River, and its public health significance. Water samples were collected from the River at different locations and depth. Samples were also taken with the use of dissecting instruments from the scale, skin, flesh, gill, and gut of S. galilaeus. Atomic Absorption Spectrophotometer was used to determine the concentration of heavy metals in the water samples and various body parts of the fish. From the result obtained, the levels of heavy metals concentrations ranged between 0.00-3.14, 0.00-2.18, 0.52-3.08, 0.00-0.68 and 0.00-1.48 mg/kg in the gill, flesh, gut, skin and scale respectively. The highest level of heavy metals was recorded in the gill while the lowest was recorded in the skin. The concentration of each of the heavy metals was significantly different across body parts (P˂0.05) except lead. Concentration of most of these heavy metals exceeded the maximum permissible limit. Our results indicated that there is inherent danger in consuming fishes from Ilo-Idimu river.