Reedfish

Overview

The Reedfish (Erpetoichthys calabaricus), universally known in the international aquarium trade and ichthyology as the Ropefish or Snakefish, is an extraordinary, archaic freshwater ray-finned fish belonging to the ancient family Polypteridae. Indigenous to the warm, sluggish coastal river basins and swampy floodplains of West Africa—stretching from the Niger Delta in Nigeria to the coastal waters of Cameroon—this mesmerizing creature represents the only living member of the genus Erpetoichthys. Exhibiting an exceptionally slender, serpentine body armored in diamond-shaped ganoid scales, the reedfish looks more like an ancient aquatic reptile or serpent than a typical fish, earning its scientific generic name Erpetoichthys, meaning ‘creeping fish.’

Scientifically, Erpetoichthys calabaricus is a celebrated ‘living fossil,’ belonging to a primitive basal lineage of ray-finned fishes (Actinopterygii) that split from all other bony fishes over 390 million years ago during the Devonian Period. Its most astounding anatomical feature is the possession of functional, paired, vascularized true lungs connected to its pharynx, enabling the reedfish to breathe atmospheric air and survive out of water in damp vegetation for extended periods. In peaceful nocturnal tranquility, it slithers through tangled aquatic root systems, utilizing its acute sense of smell to locate worms and crustaceans. Evaluated as Near Threatened on the IUCN Red List due to intensive habitat loss in the oil-rich Niger Delta, the reedfish is an irreplaceable treasure of evolutionary biology.

Biology and Physical Characteristics

Anatomically, Erpetoichthys calabaricus is a masterwork of archaic evolutionary design. Its body is extraordinarily elongated, cylindrical, and snake-like, lacking pelvic fins entirely—a unique morphological trait that distinguishes it from all other members of the order Polypteriformes (the bichirs). Its entire body is encased in a rigid, flexible armor of heavy, rhombic ganoid scales coated with a glass-like layer of ganoine, providing virtually impenetrable protection against predator bites. Along the posterior two-thirds of its back sits a segmented dorsal fin composed of 7 to 13 separate, miniature finlets, each supported by an erectile spine and delicate fin rays. Its pectoral fins are fan-shaped and set upon fleshy, muscular lobes that the fish uses to ‘walk’ or prop itself up on the river bottom. Most remarkably, its swim bladder has evolved into a pair of asymmetric, vascularized lungs; the fish gulps air at the water’s surface, extracting oxygen through lung tissue while utilizing its reduced gills primarily for carbon dioxide excretion.

Behavior and Ecology

Behaviorally, the Reedfish is a peaceful, nocturnal bottom-dweller that spends the day curled comfortably among dense submerged vegetation, hollow drift logs, or muddy crevices. As twilight descends, it emerges to prowl the riverbed with smooth, sinuous, anguilliform movements reminiscent of a swimming snake. Because its eyesight is poor, it hunts primarily using chemoreception: two prominent, tubular sensory nostrils (barbels) project from the tip of its snout, which it points in all directions to track the minute chemical scents emitted by aquatic earthworms, chironomid insect larvae, and tiny freshwater shrimp. When food is located, it approaches slowly and inhales the prey with a sudden, vacuum-like expansion of its buccal cavity. During the tropical wet season, reedfish migrate into flooded forests to spawn, where males perform an elaborate courtship dance, cupping their anal fins around the female’s vent to receive and fertilize eggs before scattering them onto aquatic mosses.

Conservation and Human Impact

The Reedfish is classified as Near Threatened by the IUCN Red List, with wild populations experiencing localized declines across its core distribution in West Africa. The primary driver of its imperilment is severe habitat destruction and petrochemical pollution across the Niger Delta of Nigeria, where extensive crude oil extraction, frequent pipeline leaks, and industrial gas flaring contaminate freshwater river ecosystems. Furthermore, large-scale clearing of mangrove forests and swamp woodlands for urban expansion and agriculture eliminates vital breeding corridors. The species is also collected in substantial numbers from the wild to supply the international ornamental aquarium trade, though captive breeding protocols are increasingly mitigating wild harvest pressures. Establishing protected freshwater reserves in the Cross River and Niger Delta basins remains essential for its long-term survival.

Interesting Factoid

The Reedfish has real, working lungs instead of just gills: if the water it lives in completely dries up, it can crawl out of the mud and slither across damp land to find another pond, and it will actually drown if it is prevented from surfacing to breathe air.