The longnose sucker forages for invertebrates around the bottom of rivers or lakes (4), and its main prey items include insects, molluscs and crustaceans as well as algae and fish eggs. The downwards-facing mouth and large lips of this species allow it to suck up its prey with ease (3). The longnose sucker is prey for larger fish, such as the northern pike (Esox lucius), bass (Micropterus species), walleye (Sander vitreus) and burbot (Lota lota), as well as certain mammal species and fish-eating birds (2).
The longnose sucker lives for up to 20 years, and spawns multiple times throughout its life (6). Spawning generally occurs between May and July, although this is dependent on the water temperature. This fish species migrates upstream into shallow areas with a gravelly substrate to spawn (6). The male longnose sucker reaches sexual maturity at around four years of age, and the female can reproduce after around five years (5).
The male longnose sucker positions itself above the female and stays in place by grasping the female with its pelvic fins. The female then vibrates its body and releases eggs, while the male fertilises them. The female can produce up to 60,000 eggs which fall into crevices within the substrate (3). The eggs are yellowish in colour and usually take around two weeks to hatch, depending on the water temperature (3).