Water gets polluted from domestic wastEs (loaded with detergents, faecal matter, etc.), fertilisers and pesticides from crop fields and industrial wastes (heavy metals, waste heat).
(i) Fertilisers and domestic wates cause eutrophication or increased organic loading and excessive growth of algae (algal bloom). This ultimtely reduces oxygen available to aquatic animals (fish, molluscs) and kill them.
(ii) Domestic wastes also carry pathogens of a number of human diseases. Some of them can causse diseases of animals as well.
(ii) Pesticies and pollutants of industrial wastes directly harm the aquatic organisms and humans.
