It has a close freshwater relative in several lakes of Ireland, known as the pollan, alternatively regarded as conspecific with it, or as a distinct species.

It has a metallic silver body, a brown or dark green back, and nearly colorless fins.

[6] Predators of the Arctic cisco include marine mammals, seabirds and large fishes such as the Dolly Varden trout and burbot.

[6] Young Arctic cisco migrate along the Beaufort Sea coast and are then aided by winds to the Colville River delta, where they are over 160 km (100 mi) from where they spawned.

[6] The largest threats to the Arctic cisco appear to be climate change and oil and gas development.