[Ebook] The New Guide to Aquarium Fish – Cypriniformes – Loaches
Being bottom-dwelling species, the loaches are either eel-like or have a triangular body crosssection, their flat bellies being in contact with the substrate. Loaches may have very small scales covering all the body; be partially scaled, in which case the scales are missing from the underside; or naked. When you think about it, the absence of some or all of the scales is a very sensible arrangement, because if scales were present on the belly of the fish, they would be dislodged as the fish moved over rocks and sharp gravel, leaving it open to infection.