Poly‐and monoclonal antibodies, raised against mammalian membrane‐bound proton pump (V‐ATPase) were applied to the bone‐resorbing cells of Oreochromis niloticus to clarify if osteoclasts of an advanced teleost species display V‐ATPase, a key enzyme in the process of bone resorption. All antibodies labelled cells at known sites of bone resorption, the endosteal bone surfaces surrounding the tooth anlagen. The best results were...