The status of Agboju, Ajegunle, Topo and Gbaji water bodies in Badagry Division of Lagos State, Nigeria was evaluated between April and November 2018 in order to determine the suitability of the ecosystem to biota and safety of the aquatic resources for human consumption. Some environmental variables such as alkalinity, temperature, biochemical oxygen demand (BOD), conductivity, total dissolved solid (TDS), carbon (iv) oxide (CO 2), total hardness, chemical oxygen demand (COD), turbidity, phosphate, dissolved oxygen (DO), pH, salinity, sulphate and nitrate, and some heavy metals (Fe, Cu, Zn, Pb, Cd and Cr) in water, sediment, aquatic plant (Eichhornia crassipes) and fish (Ethmalosa fimbriata) were measured using standard procedures. The results showed that BOD, COD, total hardness and turbidity values were above the standard permissible limits. Cd in water column of Agboju and Ajegunle, and Pb recorded from Agboju, Ajegunle and Topo, exceeded standard permissible limit. Cu (0.56±0.54), Zn (5.45±0.89), Pb (0.54±0.47) and Cr (0.455±0.375) contents in E. fimbriata (from Ajegunle) was slightly above permissible limits while Cd and Fe contents in the fish across the four stations were above permissible limits. Contamination factor, Index of geochemical accumulation and enrichment factor showed moderate degree of contamination of cadmium and Fe in the sediment. This preliminary study could be concluded that the biota can still survive in the ecosystems despite high contamination of the water bodies with metals. However, human consumption of several of E. fimbriata and water could cause health hazard. Therefore, urgent effort should be made by all users of the ecosystem to decline in discharging untreated waste into these water bodies.

The toxicity of cypermethrin (a pesticide) on fingerlings of African catfish, Clarias gariepinus was investigate with emphasis on histopathological effects. The juvenile were exposed to 0, 1.0, 2.0, 3.0, 4.0 and 5.0ppb of cypermethrin under experimental condition. The growth, nutrient utilization and feed utilization parameters (Weight gain, Average Daily Weight Gain, Percentage Weight Gain , Specific Growth Rate , Feed Intake ,Feed Conversion Ratio and Protein Intake were not significantly different(P>0.05) at the different concentration. However, histopathological changes were observed on the gills and liver of the experimental fish. In the gills, filament cell proliferation, cellular infiltration, haemorrhage and gill damage were observed. In the liver, there was vacuolation of hepatocytes and necrosis. However, there was no observable histological change in the intestine at the various concentrations of exposure. Respiratory stress, erratic swimming and instant death of fish were observed in exposed fish, which varies with the concentration of the toxicant and it showed that mortality increased with increase in concentration. This study concluded that Cypermethrin is highly toxic to fish and therefore should be avoided in aquatic ecosystem.

Forty wild adult Tilapia guineensis were sourced from Ojo and Badagry creeks between January and March 2021, to investigate its morphometric character (total length, body weight, standard length, and head depth) and tissues structure (gill, muscle and small intestine) differences. Samples were collected and analysed using standard methods. The results showed no significant difference (P<0.05) between the mean total length, body weight, standard length, and head depth of Tilapia guineensis recorded from both creeks.  Length-weight relationships of T. guineensis obtained from both creeks showed negative allometry(b<3) growth pattern while its condition factor (k) value was more significant than one, which indicated that the fishes are in good condition. Muscle of T.guineensis from Ojo creek showed a severe lesion of muscle bundle, degeneration of muscular bundle and shortening of bundles.  Similarly, the gills structure of T. guineensis from Ojo creek showed severe degeneration, hyperplasia of secondary gill lamellae, and curling of secondary lamellae with unclear water channels. It is also characterized by hypertrophy of lamellae, and there is evidence of partial fusion of lamellae and dilation of gill filament. The observation of none lesion or degenerated tissues of T. guineensis in Badagry creek could suggest that Ojo creek is more subjected to effluents or other environmental stressors than Badagry creek. In conclusion, T. guineensis from Badagry creek is less affected by any environmental contaminants than T. guineensis from Ojo creek. Therefore, a collective effort towards ensuring reduction in direct discharge of untreated effluent or avoidance of another unhygienic usage of the creeks is very pertinent.