Abstract. The northern snakehead (Channa argus) is a large piscivorous fish that is invasive in eastern Europe and has recently been introduced in North America.n the winter (November–April), these fish moved to deeper water (~135 cm) with warmer temperatures, but habitat selection was weak at both scales. Northern snakeheads returned to shallower water (~95 cm) in the prespawn season (April–June) and used milfoil and other cover.