Australian lungfish

What it is

This ancient fish belongs to the only surviving family of its kind, Neoceratodontidae. It possesses a stout, elongated body covered in large bony scales that overlap extensively for protection. The colouration ranges from olive-green or dull brown on the back to pale yellow or orange underneath, with males showing brighter reddish hues during breeding. Adults reach up to 150 cm in length and weigh around 43 kg. They have flattened heads, small eyes with unique photoreceptors, and paddle-shaped tails. Unlike other lungfish, they have large, fleshy pectoral and pelvic fins.

Where it lives

Native exclusively to the Mary and Burnett River systems in south-eastern Queensland, Australia. Historical introductions occurred in the Brisbane, Albert, Stanley, Coomera, Pine, Caboolture, and Condamine Rivers, though survival in these new areas is uncertain. The species prefers slow-flowing rivers and still waters containing aquatic vegetation. It inhabits mud, sand, or gravel bottoms, typically residing in deep pools between three and ten metres. It tolerates cold but thrives in water temperatures ranging from 15 to 25 degrees Celsius.

How it lives

The lungfish is largely sedentary, staying within a single pool or two adjacent ones throughout its life. It does not follow migratory paths but moves toward spawning sites between July and December. It breathes air using a single dorsal lung when water oxygen levels drop due to heat or activity. This facultative air breathing allows it to survive out of water for days if kept moist, unlike African relatives that burrow in cocoons. It is generally inactive during the day but becomes more active in the late afternoon and evening, capable of rapid escape movements using its strong tail.

Breeding and life cycle

Maturity is reached late, around 17 years for males and 22 for females. Spawning occurs from August to November, triggered by day length, in flowing streams over one metre deep. Pairs deposit adhesive eggs among aquatic plants, avoiding algae-covered or stagnant areas. The female lays few eggs, roughly a few hundred in her lifetime, often spaced singly. Eggs hatch after three to four weeks into tadpole-like larvae without external gills. Young grow slowly, feeding once the yolk sac is absorbed, and can reach significant size under optimal conditions.

Fish and people

The settlement of Ceratodus in Queensland derives its name from this species. Named by Gerard Krefft in honour of politician William Forster, it holds scientific value as a living fossil. Its lineage dates back 380 million years, with fossils showing minimal change over 100 million years. One individual, Granddad, lived in the Shedd Aquarium in Chicago for over a century, dying in 2017 at an estimated age of 109. This record highlights its status as one of the longest-living subtropical freshwater fish known to science.

Status and threats

The species is classified as Least Concern globally, though local populations face threats. Habitat degradation, pollution, and dam construction can impact river flows essential for spawning. While historically widespread with seven species in Australia, only this one remains. Conservation efforts focus on protecting the Mary and Burnett River systems. Introductions to other rivers have had mixed success, raising concerns about genetic integrity and ecological balance. Research continues to monitor population health and breeding success in both wild and captive environments.

Relatives and look-alikes

It is one of six extant lungfish species, distinct from the five others found in Africa and South America. These relatives differ significantly in morphology and behaviour, such as their ability to estivate in mud cocoons. The Australian lungfish is the outgroup to all other members of the Dipnoi lineage. Fossil records indicate it has remained virtually unchanged for over 100 million years. Other extinct lungfish species once inhabited Australia, but Neoceratodus forsteri stands alone as the sole survivor of its family.

Questions people ask about Australian lungfish

Good reading and sources

• Australian lungfish on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data