Fish as a Sustainable Biomonitoring Tool in Aquatic Environments

Biomonitoring involves the use of biological organisms to detect or measure the presence of various toxic substances rather on land or in water. Fish resides in aquatic environments and its position at the top of the food chain in aquatic environments has made it a useful tool for biomonitoring. They can easily accumulate pollutants that are bio-available in the aquatic environment, most especially in their gills. The composition, abundance, and distribution of fish species can give a potential indication of the condition of aquatic environments. Other organisms such as crustaceans, zooplankton, and macro and micro invertebrates can also be used because they are ubiquitous. The condition of aquatic environments is principally dictated by the effects of land-based activities, which principally affect the water quality and composition. Humans on the other hand are exposed to bio-accumulated pollutants when aquatic organisms such as fish and aquatic plants are consumed from such polluted aquatic environments. In lieu of this, it is therefore essential to sustainably biomonitor aquatic environments, either with the use of fish or aquatic plants as a tool. Productivity is also impaired in polluted aquatic environments as primary production is inhibited because of the increased concentration of organic wastes. The responses of fish when used as a pollution biomonitoring tool can be recorded in the form of their percentage mortality, enzymatic responses, histological responses, electrolyte responses, haematological responses, and genotoxicity and DNA changes. The environment and its biotic and abiotic components can affect the use of fish as a tool, and it may be regulated by the biomarker application approaches. Conversely, sustainable approaches to the use of fish as a biomonitoring indicator can also be geared. This review, therefore, emphasizes the use of fish as a sustainable biomonitoring tool, their population and composition in relation to pollution, human health monitoring, aquatic plant monitoring, the various behavioural responses of fish to pollution, the environmental factors that can affect aquatic pollutants, and the sustainable approaches that can be employed in the use of fish as a tool for biomonitoring indication.