Hello Maruf Adnan

Catfish possesses a pair of suprabranchial chambers located in the dorsal-posterior part of the branchial cavity having extensions from the upper parts of the second and fourth gill arches, forming the arborescent organs. This structure is an air-breathing organ (ABO) and allows aerial breathing.

In stale waters which is not properly aerated or small water bodies or even in mud without water, the catfish will breathe air using the air-breathing organ for their survival. The oxygen is extracted as a gas from the atmosphere by the catfish.

So, catfish can use their gills when they in water that is aerated as well as use their air-breathing organ or air bladders when water is scanty or not well aerated.

Best.