CLARIAS,HETEROPNEUSTES

Cat fish clarius batrachus  has accessory respiratory organs.These are in the formof two much branched tree-like dendritic or arborescent organs developed inside suprabranchial cavities one on either side above the gill chambers. The cavities and the organs are covered by vascular mucous epithelium and functions as lungs. The fish periodically reaches watter surface to renew air.
HETEROPNEUSTES-This catfish has a pair of long tubular and dorsally situated air sacs arising posteroorly from gill chambers and extending almost up to the tail.They are highly vascular .The air is drawn in and expelled out through pharynx.