The Mary River Cod (Maccullochella mariensis) is a large, deep-bodied freshwater fish native to the Mary River system in southern Queensland, Australia. It exhibits a golden-yellow to dark green or brown coloration with dark mottling. Historically, individuals could reach up to 120 cm in length and 40 kg in weight, though most contemporary specimens are smaller. As an ambush predator, it feeds on various aquatic organisms. Due to overfishing and habitat degradation, it is now one of Australia's most endangered freshwater fish species.