African Lungfish

The African Lungfish is a freshwater fish belonging to the family Protopteridae, part of the ancient lungfish lineage (Dipnoi) more closely related to tetrapods than to most modern fish. The genus Protopterus contains four recognized species distributed across sub-Saharan Africa, with Protopterus annectens among the most widespread. It possesses true paired lungs and can survive prolonged drought by burrowing into mud and entering a dormant state called estivation. This remarkable adaptation allows it to persist in seasonal wetlands that dry out completely for months at a time, a survival strategy virtually unmatched among vertebrates and of significant interest in the study of vertebrate evolution.

Key identification features of the African Lungfish:

• Body shape: long, eel-like, and cylindrical with smooth-looking skin
• Fins: paired fins reduced to thin, whip-like filaments rather than typical fan-shaped fins
• Coloration: mottled grey-brown to olive with darker blotches, providing camouflage in murky water
• Head: blunt and rounded with small eyes
• Fin arrangement: dorsal, tail, and anal fins merge into a single continuous fringe around the rear of the body

Its thread-like paired fins immediately distinguish it from true eels, which have fan-shaped pectoral fins, and from other freshwater fish of similar shape.

African Lungfish inhabit slow-moving rivers, floodplains, swamps, and seasonal pools across much of sub-Saharan Africa, including West and Central African river systems. They favor warm, often oxygen-poor water with soft muddy bottoms suitable for burrowing. When their habitat dries during the dry season, they burrow into the mud, secrete a protective mucus cocoon, and enter estivation, remaining dormant until rains return and refill their wetland habitat. This adaptation allows them to occupy temporary water bodies that most other fish species cannot survive in, giving them access to habitat largely free of aquatic competitors during wetter periods.

African Lungfish are primarily nocturnal, air-breathing predators that rely on true lungs in addition to gills, regularly surfacing to gulp air even in well-oxygenated water. During the dry season they undergo estivation, slowing their metabolism dramatically while encased in a mucus cocoon buried in dried mud, a dormancy that can last many months until rains return. They are generally solitary and can be aggressive toward other fish, using strong jaws to crush prey such as mollusks, crustaceans, and smaller fish. Reproduction occurs in flooded vegetation during the wet season, with some species known to guard nests and young aggressively.