Persistence of pollution into our natural environment has concurrently led to instability, disorder, harm or discomfort to both the physical systems and living organisms inhabiting the ecosystem. Potentially harmful substances such as pesticides, heavy metals, paper mill waste, polychlorinated biphenyl and crude oil are often released into the aquatic environment. When large quantities of these pollutants are released there may be an acute impact as measured by large-scale sudden mortalities of aquatic organisms such as fish kills. Lower levels of discharge may result in an accumulation of the pollutants in body composition of fish. The effects of water pollution on fish species can be classified into acute effects and long term chronic effects, which includes immune-suppression, reduced metabolism, and damage to gills and epithelia. Pollution-related diseases include fin/tail rot, gill disease, hepatic damage and ulceration. Specific examples of fish diseases that reflect the effects of pollution include, fin and tail rot caused by Amnonas hydrophila and Pseudomonas jluorescens. The polluted water may have undesirable colour, odour, taste, turbidity, harmful chemical contents, toxic and heavy metals, pesticides, industrial waste products, domestic sewage, virus, bacteria, protozoa and worms. Fish species are not only tolerant to severe contaminated waters but show a variety of specific morphological deformities and lesions that appear to reflect the level of water pollution. Assessing morphological deformities is one of the most straightforward methods to study the effects of contamination on fish because of the ease of recognition and examination when compared with other types of biomarkers. The indiscriminate disposal of pollutants without pre-treatment should be discouraged. In order to avoid the effects of water pollution on fish health, effluents discharged from industries and other sources should be properly treated.

Wetlands are water body in the terrestrial or semi-terrestrial ecosystem characterized with low drainage, soil, and plant. Wetlands are very important and valuable components of the ecosystem. They serve as habitat for man and animal, source of food, shelter and other ecosystem services etc. There are different wetlands in the world and Nigeria owns one of the internationally recognized wetlands in the world, the first wetland recorded as a Ramsar site. Hausa, Kanuri and Fulani are the most pronounced tribes that dominate the area. The resources attributed to the wetlands in Nigeria are highly valuable; they contain fish, reptile species, mammal species, amphibian species, and bird's species. In Nigeria, the Hadejia-Nguru wetlands is a wide expanse of floodplain wetlands, which is situated in the North-East Nigeria; it is located in the Sudanosahelian zone, which is the zone between the Sudanian Savanna in the south and the Sahel in the North. Some of the activities carried out on the Hadejia-Nguru wetlands include fishing, agriculture and tourism activities. There are different challenges facing wetlands globally, some of which are pollution, over intensification of agriculture activities, industrialization and urbanization. Some of the challenges in wetlands are due to the lack of monitoring and sustainability measures from government and lack of awareness of the inhabitants.

This study examines the effect of physicochemical parameters on different categories of fish species; benthopelagic, pelagic and demersal on Lake Volta. The methods of this study were based on the estimation of hydrographic data, collection and analysis of physicochemical parameters of the water samples. Fish samples were collected from four sampling stations namely Oti River at Sabra, White Volta at Daboya, Black Volta at Bamboi and Lower Volta at Amedeka. This review work studies a study which was carried out between February 1995 and January, 1996. A statistical analysis was conducted. Water resource availability and mean annual rainfall of Lake Volta were highest in Black Volta and Oti River respectively. The results show pH 194-520, Conductivity (μS cm -1 ), Dissolved oxygen 8.

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