Australian Lungfish

The Australian Lungfish is a freshwater fish endemic to a small number of river systems in Queensland, Australia, and is the sole living member of the family Ceratodontidae. It is considered one of the most primitive living bony fish, with a fossil record showing remarkably little change over more than 100 million years, earning it recognition as a living fossil. Unlike African and South American lungfish, it possesses a single lung rather than paired lungs and relies primarily on gills for respiration, using its lung mainly as a supplemental air source in poorly oxygenated water. The species is legally protected in Australia due to its restricted natural range and vulnerability to habitat change.

Recognize an Australian Lungfish by these traits:

• Body: large, heavy-bodied, and covered in thick overlapping scales, olive-brown to grey with scattered dark blotches
• Fins: broad, fleshy, paddle-like pectoral and pelvic fins, distinct from the thread-like fins of African lungfish
• Fin continuity: dorsal, tail, and anal fins merge into a single continuous fringe around the rear of the body
• Size: adults commonly reach 1 to 1.5 meters
• Behavior cue: surfaces occasionally to gulp air but breathes mainly through gills, unlike more air-dependent lungfish relatives

Its broad, paddle-shaped fins clearly separate it from the thin, whip-like fins of African lungfish species.

The Australian Lungfish is restricted to a small number of river systems in southeastern Queensland, most notably the Mary and Burnett Rivers, with additional populations established through translocation to nearby catchments. It favors slow-flowing to still, deep pools within freshwater rivers, often among aquatic vegetation, and generally avoids fast-flowing or highly turbid stretches. Unlike African lungfish, it does not burrow into mud or estivate during dry periods, instead relying on permanent, well-oxygenated pools even in drier months. Its highly restricted natural range makes the species particularly sensitive to changes in river flow, water quality, and barriers such as dams that can fragment its habitat.

Australian Lungfish are generally slow-moving and largely nocturnal, using their broad paddle-like fins to move gently through vegetation while foraging along the riverbed for a mix of plant material, invertebrates, and small aquatic animals. They breathe mainly through gills, surfacing to gulp air with their single lung only when dissolved oxygen levels drop, unlike the African lungfish species that rely more heavily on aerial respiration. Spawning occurs in spring within dense aquatic vegetation, where eggs are attached individually to plants without further parental care. The species is notably long-lived, with individuals documented living well over 50 years, and its slow reproduction and restricted range make population recovery from habitat disturbance especially slow.