Ansorge's bichir

Polypterus ansorgii

Also known as Guinean bichir

FreshwaterFish

Care at a glance

Temperature: 75–82°F (24–28°C)
pH: 6.2–7.8
Adult size: 15.7 in (40 cm)
Minimum tank: 119 gal (450 L)
Temperament: Mostly peaceful
Social behavior: Solitary
Tankmates: Tankmates with caution
Swim level: Bottom
Difficulty: Medium
Breeding: No record
Rarity: Rare
Origin: Upper Guinea rivers, West Africa
Family: Polypteridae

Overview

Ansorge's bichir is a rare West African oddball kept the classic bichir way: a nocturnal, lurk-and-lunge predator that patrols the bottom and will eat any tankmate small enough to swallow. Keep it on its own or only with robust fish too large to become a meal, never with small community fish. Plan for an adult around 40 cm, since aquarium fish outgrow the smaller figures often quoted for the species, so allow a big footprint of at least 450 liters and ideally more. Feed meaty foods such as earthworms, prawn, mussel and sinking carnivore pellets in the evening, and fit a tight, weighted lid, because bichirs climb out.

In the wild

It comes from forest rivers of Guinea and Guinea-Bissau in Upper Guinea, West Africa, slow, shaded, tannin-stained waters over soft bottoms. Recreate that with a sand or fine-gravel floor, driftwood, rockwork and shade from tall or floating plants, with gentle flow. Keep the water soft to medium and from slightly acidic to slightly alkaline, about pH 6.2 to 7.8, and warm at 24 to 28 C. Subdued lighting brings this nocturnal fish out.

Good to know

Polypterus ansorgii is a bichir in the family Polypteridae, an ancient line of ray-finned fishes sheathed in hard, glossy scales. A 2019 revision of the family measured preserved specimens to 24.6 centimeters and recorded one aquarium fish at 37.1 centimeters, which is why a planning size near 40 centimeters is safer than the lower figures often quoted. Its breeding is not recorded in home aquaria; like its kin it would scatter eggs among plants rather than guard a nest.

Did you know

It is a fish keepers argued over sight unseen. Ansorge's bichir is one of the rarest bichirs in the trade, so seldom exported that for years it was known mostly from museum specimens rather than living examples.