Home / Fishes / Arowanas and elephantfish / African brown knifefish
No federal permit to keepAfrican brown knifefish
Xenomystus nigri
Fishes › Arowanas and elephantfish (Osteoglossiformes) › Notopteridae (Asian and African knifefish)
The African brown knifefish (Xenomystus nigri) is the only species in the genus Xenomystus of the family Notopteridae.
Care at a glance
Species-specific aquarium care
- Tank: At least 48 in long and 24 in front to back for one adult (adults commonly reach about 11.8 in / 30 cm).
- Water: Freshwater.
- Temperature: 72–82°F (range recorded for this species).
- pH: 6–8.
- Hardness: 5–19 dGH.
- Layout: Lives on or near the bottom: floor space and hiding places matter more than height.
- Diet: A predator: feed meaty foods sized to its mouth (frozen fish, shrimp, worms); it will eat tankmates that fit in its mouth. FishBase classes it as a carnivore.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 47 × 18 in (roughly 54 US gallons); space needed is rated “large tank”.
- Water: a fairly wide range, from slightly acidic to slightly alkaline, 73–82 °F, pH 5.8–7.5, 1–20 dGH.
- Difficulty: Easy (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Ideally the tank should contain some areas of dense planting.”
- Tankmates: “Do not keep with any fish so small as to be regarded as food.”
- Breeding: “Has occured in aquaria but infrequently and few details are available.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Asian and African knifefishes
Applies to most species in this group. Habitat: Notopterids inhabit African and Asian freshwaters, including still, vegetated waters, rivers, lakes and floodplains, with Chitala ornata entering flooded forest to spawn. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- For Xenomystus nigri, the cited lifetime aquarium is approximately 120 x 45 x 38 cm, about 205 litres, for one fish.
- For Chitala ornata, plan a public installation or exceptionally large specialist aquarium: adults reach about 100 cm standard length.
- Provide dim light and refuges made from smooth wood, rocks or appropriately sized pipes; planted cover and soft sand particularly suit X. nigri.
- For large Chitala, install mature filtration, oxygenated water and substantial regular water changes; the C. ornata reference specifies 50–70% weekly.
- Preserve access to the water surface for atmospheric breathing.
Diet
- Bloodworms and earthworms, with smaller portions for juveniles.
- Prawns or shrimp and chopped mussels.
- Marine fish flesh for larger Chitala.
- Carnivore pellets if accepted, with varied meaty foods rather than pellets alone for C. ornata.
Social life
- Keep fish too large to swallow as any companions; provide separation for territorial adults. X. nigri becomes less tolerant of its own species with maturity, and Notopterus notopterus is more aggressive.
Health watch
- Nutritional organ damage from unsuitable mammalian or avian meat in Chitala.
- Ammonia toxicity under inadequate filtration.
- White spot disease, a general freshwater aquarium risk.
Understanding the animal
About this animal
About this animal
This fish is found in the Chad, Nile, Congo, Ogowe and Niger basins, as well as coastal river basins in Sierra Leone, Liberia, Togo, Benin and Cameroon.
Quoted from the Wikipedia article “African brown knifefish” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in rivers and streams, lakes. Stays near the bottom. Prefers quiet waters with vegetation. Females lay 150-200 eggs of 2 mm diameter. |
| Water it lives in | Freshwater, 72–82 °F (22–28 °C), pH 6–8, hardness 5–19 dH. |
| Climate | Tropical climate. |
| Wild diet | Hunting macrofauna (predator). |
| Behavior to plan for | Breeding: paternal parental care. |
What this means for care
- Keep water within its wild range, 72–82 °F.
- Parents guard eggs or young, so expect territorial behavior when breeding.
Native climate (measured)
Native climate (measured)
| Warm-season highs | about 88°F (up to 92°F in the hottest sampled areas) |
| Cool-season lows | about 67°F (down to 63°F in the coldest sampled areas) |
| Average temperature | 76–81°F across sampled records |
| Relative humidity | 78–83% on average (driest month about 76%) |
| Rainfall | about 1686 mm a year |
Measured at 105 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Overview | The African brown knifefish (Xenomystus nigri) is the only species in the genus Xenomystus of the family Notopteridae. This fish is found in the Chad, Nile, Congo, Ogowe and Niger basins, as well as coastal river basins in Sierra Leone, Liberia, Togo, Benin and Cameroon. — Wikipedia (community-edited) |
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Appearance and size | This fish reaches 30 cm (12 in) in standard length. The body of these fish is unusual; it is ventrolaterally flattened and elongated, giving the appearance of a knife blade. The caudal and anal fins are fused and run from beneath the gill opening to the pointed end of the body, creating a uniform, skirt-like fin. — Wikipedia (community-edited) |
| Biology | Obligate air-breathing; Prefers quiet waters with vegetation. Females lay 150-200 eggs of 2 mm diameter. Can produce barking sounds. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Maximum recorded lifespan
Longest recorded lifespan reported by each database; typical lifespans are usually shorter. The AnAge record comes from an animal in human care.
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates in nature; aim for the middle.
Minimum tank footprint
Seriously Fish recommends a tank base of at least 47 × 18 in (about 54 US gallons).
Sources for this sheet
- AnAge: The Animal Ageing and Longevity Database (Human Ageing Genomic Resources) Peer-reviewed researchCurated, referenced longevity and life-history records for thousands of species; maximum lifespans are often from zoo animals.
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Seriously Fish: Xenomystus nigri Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Seriously Fish: Chitala ornata Experienced keeper or breederAdded in the 2026 source-checked care-guide review.
- Merck Veterinary Manual: Disorders and Diseases of Fish Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
- iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.
More asian and african knifefish
Bronze featherback
Notopterus notopterus
Aquarium hobby
Clown featherback
Chitala ornata
Aquarium hobby
Clown knifefish
Chitala chitala
Aquarium hobby
Reticulate knifefish
Papyrocranus afer
Aquarium hobby
Royal knifefish
Chitala blanci
Aquarium hobby