### Identification The *Gyrinocheilus aymonieri*—often called the Honey Sucker or Chinese Algae Eater—is a streamlined, muscular bottom-dweller reaching up to 11 inches in the wild. Its most striking feature is its inferior suctorial mouth, a powerful vacuum-like disc designed for anchoring in torrential currents. Wild specimens are an understated olive-brown with a distinctive row of dark, blurred blotches along the lateral line. In the aquarium trade, you’ll more likely spot the "Gold" morph, a vibrant xanthic yellow. To distinguish it from the Siamese Algae Eater (*Crossocheilus oblongus*), look for the absence of barbels and the presence of a unique, small opening at the top of the gill cover—a specialized "spiracle" used for respiration.
### Habitat & Range This species is a specialist of the Mekong, Chao Phraya, and Mae Klong basins in Southeast Asia. They are masters of the "benthos," preferring sun-drenched, fast-flowing rivers and streams with rocky or gravelly substrates. You won't find them in stagnant swamps; they crave the high oxygen levels and turbulent flow of highland rapids where periphyton (biofilm) grows thick on submerged boulders.
### Behaviour While they may look docile, these are combative loners. As they mature, they become increasingly territorial, defending "grazing patches" from rivals. An observer will notice their jerky, undulating swimming style, punctuated by long periods of being "glued" to rocks. They are diurnal, spending the daylight hours in a constant "rasping" dance, moving their mouths rhythmically across surfaces.
### Diet The *Gyrinocheilus aymonieri* is a specialized grazer. Using horny, "toothed" ridges inside its mouth, it scrapes periphyton—a complex mix of algae, cyanobacteria, and microbes—off slippery rocks. While primarily herbivorous, they are opportunistic; as they age, they may supplement their diet with aquatic invertebrates or even the protein-rich slime coats of larger, slow-moving fish.
### Fascinating Fact Most fish must take water in through their mouths to breathe, but this species has evolved a "bypass" system. Because its mouth is often occupied by suctioning onto rocks in heavy currents, it has a modified gill slit that allows it to draw water directly into the gill chamber from the side of the head, effectively breathing while its "lips" are sealed tight!