Kerala, on the South Western tip of Peninsular India is blessed with the South western and South Eastern monsoon which contributes to its vast fresh water bodies. But pollution of these water bodies has created physiological stress on its aquatic fauna. Among various forms of pollution in water bodies, detergent pollution has an immediate and detrimental effect on the aquatic fauna. Anabas testudineus, a common fresh water fish in Kerala was used in our study to determine the effect of detergent pollution on the fish’s breathing.