Senegal bichir

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: sand.

Behavior

Plant interaction: may nibble soft.

Feeding

Sinking carnivore pellets, frozen bloodworms, prawns, silversides, earthworms. Poor eyesight; hunts by smell. Feed at lights-out for best feeding response. Will eat any fish small enough to swallow.

Nocturnal feeder; drop food after lights out.

Compatibility

• Living fossil. Polypteridae have existed for 100+ million years; the dorsal finlets, ganoid scales, and lobed pectoral fins are all primitive features
• Obligate air breather. Must have access to the surface; they drown in nets or traps that prevent surfacing. The lung is a modified swim bladder
• Escape artist. Will find any gap in the tank lid and push through it. Bichirs can survive out of water for hours breathing air, so you may find one on the floor still alive
• The 'dinosaur eel' common name is doubly wrong (not a dinosaur, not an eel) but it sells fish to people who want something unusual
• Compatible with similar-sized non-aggressive fish: large peaceful cichlids, larger catfish. Will eat anything it can fit in its mouth, which is wider than it looks

Origin and habitat

Polypterus senegalus, the Senegal or gray bichir, is the most widespread member of the bichir family, Polypteridae, an ancient lineage of ray-finned fish often called living fossils for their lobed pectoral fins, dorsal finlets, and armour of rhombic ganoid scales. Cuvier described it in 1829. It ranges across tropical Africa from the Senegal and Gambia rivers through the Niger, Volta, and Chad basins to the Nile, with a southern subspecies in the Congo. It lives in shallow, slow, vegetated swamps and river margins, and like all bichirs it breathes air with a lung-like divided swim bladder, surviving out of water as long as it stays moist and even crawling overland on its pectoral fins. It hunts mainly by smell, having poor eyesight. Records list a maximum standard length around 70 cm, but that is far above the typical size; the species is one of the smaller bichirs, usually reaching about 35 cm, which is part of why it is the most commonly kept bichir and a good first one. Colour is usually grey to beige, sometimes blotched, and albinos are traded.

Breeding

Breeding is uncommon in home aquariums but does happen in large, well-fed setups warmed into the high twenties. In the rains the male chases and nudges the female, then cups his anal and caudal fins around her to receive the eggs, fertilise them, and scatter them into vegetation; a female may lay on the order of a hundred to a few hundred eggs over several days. The eggs hatch in three to four days, and the larvae are unusual in carrying feathery external gills, like an axolotl's, for the first weeks before these are absorbed. The fry finish their yolk over about a week and then take small live foods such as baby brine shrimp and microworms.

Common problems

It is a predator that swallows anything it can fit in a mouth wider than it looks, so small fish and shrimp vanish overnight; tankmates need to be too big to eat. The other classic issue is escape: with its air-breathing lung a bichir can survive a long spell on the floor, and it will push through any gap, so a heavy, well-sealed lid is essential. Poor eyesight makes feeding slow, since it tracks food by scent, so in a mixed tank faster fish can clear the food before the bichir finds it, and feeding after lights-out helps. They are otherwise hardy and extremely long-lived, with captive ages past thirty years on record.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size