In fish, a suckermouth is a ventrally-oriented (inferior) mouth adapted for grazing on algae and small organisms that grow on submerged objects (aufwuchs). In general many benthic dwelling or feeding fish will have a suckermouth feature. Many of these fishes originate from fast-moving waters, where the sucker allows the fish to 'stick' itself down without too much difficulty.

All Loricariidae possess