Bichir
Archaic ray-finned fishes with lungs and dorsal finlets.
Bichirs and the reedfish comprise Polypteridae, a family of archaic ray-finned fishes and the only family in the order Polypteriformes. All species occur in freshwater habitats in tropical Africa and the Nile River system, mainly swampy, shallow floodplains and estuaries.
- field
- Ichthyology
- known_for
- Archaic ray-finned fishes with paired lungs and dorsal finlets
- native_region
- Tropical Africa and Nile River system
- oldest_fossil_age
- Around 100 million years old (early Late Cretaceous)
- maximum_length
- 25 cm to over 100 cm depending on species
Lore & Background
Polypterids are elongated fish with a unique series of dorsal finlets varying from seven to 18, instead of a single dorsal fin. Each finlet has bifid tips, and they are the only fins with spines; the rest are composed of soft rays. Their body is covered in thick, bonelike, rhombic (ganoid) scales, and their jaw structure more closely resembles that of tetrapods than of teleost fishes. They have fleshy pectoral fins superficially similar to those of lobe-finned fishes, a pair of slit-like spiracles on top of their heads for air breathing, two gular plates, and paired ventral lungs.
Reader's Guide
Their anatomy preserves primitive features such as ganoid scales, fleshy pectoral fins, and paired lungs, offering insights into the evolution of air breathing and the transition from fish to tetrapods. They are facultative air-breathers, using recoil aspiration via spiracles or mouth, and their lungs are smooth sacs unlike the alveolated tissue of lungfish and tetrapods. In captivity, they are popular aquarium subjects with life expectancies of 10–30+ years, known for their dragon-like appearance and peaceful nature when kept with appropriately sized tankmates. Their classification includes two living genera, Polypterus and Erpetoichthys, with 14 extant species, and fossil relatives such as Bawitius from the Late Cretaceous.
Did You Know?
- Polypterids have a pair of slit-like spiracles on top of their heads used to breathe air.
- Their lungs are unchambered sacs; the right lung reaches the whole length of the body cavity.
- They breathe using recoil aspiration, a unique method among fishes.
- The oldest polypterid fossils are around 100 million years old, from the early Late Cretaceous of South America and Africa.
Frequently Asked Questions
What is a bichir?
A bichir is a member of the family Polypteridae, the only family in the order Polypteriformes. It is an ancient ray-finned fish distinguished by a row of small dorsal finlets and a pair of functional lungs.
What makes bichirs unique among ray-finned fishes?
Bichirs breathe air through true lungs, a trait virtually absent in other actinopterygian lineages. They also carry numerous independent dorsal finlets along the back instead of a single fused dorsal fin.
Where do bichirs live in the wild?
Every bichir species is restricted to freshwater habitats in tropical Africa and the Nile River system. They typically occupy shallow, slow-moving floodplains, swamps, and brackish estuaries.
How old is the bichir lineage?
The earliest known bichir fossils date to roughly 100 million years ago, in the early Late Cretaceous. That makes them one of the oldest continuously surviving ray-finned fish lineages.
How big do bichirs get?
Size varies widely across the family, from species that top out near 25 cm to others exceeding 100 cm in total length. The range reflects the considerable diversity among the roughly twenty recognized species.
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