Ruhi fish have two gill chambers on either side of their pharynx. Each gill chamber is lined by conca. Each gill chamber has five gill arches. The first four gill arches bear one gill each. But the fifth gill arch has no gills. That is, there are four pairs (8) of gills in two gill chambers. Gills are the main respiratory organs of fish. Each gill arch has two gill rows. The inner edge of the gill arch expands to form the gill raker. Siddique Publications