How do mountain-stream ostariophysans scrape algae from rocks?

Mountain-stream ostariophysans, such as those in the families Gyrinocheilidae, Balitoridae, and Loricariidae, scrape algae from rocks using specialized suckerlike lips. These fishes have evolved these modified mouthparts to feed efficiently in their environment, often possessing minute or entirely absent teeth.1

To maintain their position while feeding in the rapid currents of mountain streams, these fishes often utilize additional structural adaptations, such as adhesive organs on the thorax or suction disks formed by their fins, which act as holdfasts to anchor them to the rocky surfaces.23