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.

Human and ecological disorder experienced in industrial settlements as a result of improper disposal of chemicals such as textile effluent calls for careful surveillance on the state of the environment. This study investigated the toxicity of textile effluent discharge using biochemical and cytogenetic responses to ascertain the acute and sub lethal effects on Clarias gariepinus. The 96 h LC50 of C. gariepinus exposed to the textile effluent was 8.203 ml L(-1). Fourteen day exposures to 1, 2, 4 and 6 ml L(-1) doses were conducted and several toxicological endpoints were evaluated. Sub lethal genotoxicity and biochemical study was also carried out for fourteen days. The genotoxicity studies utilized micronucleus test while the biochemical studies quantified serum anti-oxidant status Total Protein (TP), Catalase (CAT), Superoxide Dismutase (SOD) and Malondialdehyde (MDA) of the exposed fish. Toxicity factor indicates that the 96 h LC50 was significantly more toxic than the 24 h LC50 (p < 0.05). The textile effluent at the tested concentrations induced micronucleus and nuclear abnormalities in the peripheral blood of exposed fish. Micronucleus, notch and binucleated cell formation were significant (p < 0.05) compared to control while lobed and blebbed cells were insignificant (p < 0.05). SOD, TP and CAT significantly (p < 0.05) decreased compared to control group while MDA increased compared to control but was insignificant (p > 0.05). The results obtained from this study showed that textile effluent increase cytogenetic damage and altered anti-oxidant status in C. gariepinus. Chemicals in the effluent can be bioaccumulated and biomagnified in the aquatic organism hence affecting man.

The fish abundance was determined by monitoring and recording the fish-catch data at the Otto Jetty in the Ologe lagoon. The diversity indices used for the purpose of this project were Species richness (S) and Shannon-Weiner index (H´). Three fish species from the lagoon were used for the micronucleus assay and nuclear aberrations; these are Tilapia guineensis, Sarotherodon melanoteron, and Chrysichthys nigrodigitatus. Diversity indices (H) obtained for the months of June, July, August and September were 2.61, 2.54, 2.54, 2.61 respectively while evenness (J) for the months were 0.64, 0.60, 0.53, 0.44 respectively. Apart from the presence of micronucleus, the genotoxicity assay also showed the presence of binucleated nucleus and blebbed nucleus. These are evidences that Ologe lagoon has a certain level of pollution, though in a minimal level. As advanced by this research work, there is great variation in fish composition and abundance in Ologe lagoon in relation to changes in the physical and chemical state of the water in the lagoon during the months of this research and this is very crucial to the biological life of the lagoon. However, anthropogenic activities should be regulated so as to prevent the level of pollution from increasing beyond tolerable limits.

A plant has become a preferred source of protein for fish species in aquaculture. A twelve-week feeding trial was carried out in order to assess the effect of feeding walnut leaves on haematological and biochemical parameters as well as the genotoxicity level on Clarias gariepinus fingerlings as a bio-indicator of their health status and overall response of the fish towards the experimental diets. One hundred and fifty fingerlings of Clarias gariepinus of mean weight 6.90±0.2g were stocked randomly as ten fish per tank (52.5 X 33.5 X 21 cm 3) in triplicate. Fish were fed to satiation and the water changed every day to maintain good water quality. Five experimental diets with 40% crude protein each were formulated; the control, without the test ingredient and the other four diets (test diets1, 2, 3 and 4) contained 25%, 50%, 75% and 100% inclusion respectively. The Control diet had the highest mean weight gain (P < 0.05) (118.8±17.3) among the entire group. A similar pattern was observed in specific growth rate. The least significant (P < 0.05) feed conversion ratio was recorded by the Control diet(0.68±0.03), the diet also recorded the best protein efficiency ratio (3.53±0.23).The genotoxicity test shows that some Micronucleus of the test diets were normal, lobed and binucleated nucleus compared to the Control diet. The fish fed with T. conophorum showed a significant difference in haematological values when compared to the values of fish fed the control diet. The fish fed with T. conophorum showed a significant difference in biochemical value when compared with control diet. There was a reduction in the biochemical values of the fish fed T. Conophorum with Cholesterol (2.20±0.05) Albumin (8.35±0.21) and Triglyceride (0.98±0.13) compared with the values of fish fed with the control diet with cholesterol (3.81±0.07) Albumin (12.35±2.33) and Triglyceride (7.29±7.02). It was concluded that using T. Conophorum leaves as feed for Clarias gariepinus enhances the growth of the fish. Therefore, partial replacement of feed T. Conophorum should be encouraged.

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