- Common name
- African knifefish
- Scientific name
- Xenomystus nigri
- Category
- Freshwater fish
- Group
- Knifefishes and specialist fish
- Environment
- Freshwater aquarium
- Origin
- Tropical Africa: Nile, Chad, Niger, Ogowe and Congo basins, plus selected coastal rivers from Sierra Leone to Cameroon
- Care level
- Advanced
- Adult size
- Up to 30 cm standard length
- Expected lifespan
- No dependable species-specific maximum was located; plan for at least 8–12 years of specialist nocturnal-predator care.
- Minimum housing
- At least 500 L with a 150 cm or longer footprint, deep dim refuge and unobstructed surface access
- Temperature
- 22–28 °C
- pH
- 6.0–8.0
- Hardness / minerals
- 5–19 °dH (approximately 89–339 mg/L as CaCO₃)
- Salinity
- Freshwater; 0 ppt routine salinity
- Lighting
- Subdued, with deep shaded cover
- Placement / zone
- Bottom and middle water; surface for air
- Filtration
- Use mature biological filtration sized for the complete adult african knifefish group, with guarded intakes and accessible mechanical capture. Keep flow gentle to moderate in open areas while retaining calm dark refuges where the fish lives, and maintain undetectable ammonia and nitrite.
- Aeration
- Maintain reliable surface agitation and oxygen exchange at all times. Increase aeration during warm weather, medication, transport recovery, heavy feeding or any sign of rapid breathing.
- Maintenance
- Perform regular matched-water changes guided by nitrate and waste, remove uneaten food and trapped detritus, clean mechanical media without disrupting the biofilter, and record feeding, body condition, respiration and aggression.
Identity and search names
Single-species profile for Xenomystus nigri. Preserve permanent AquaNexus ID 1258, slug african-knifefish and route species/african-knifefish/index.html; retain former combinations, locality labels and trade names only as searchable aliases.
Search names: African brown knifefish
Environment and housing
Quiet, heavily structured aquarium with plants or wood, several dark refuges, gentle areas, strong biological filtration and a tight lid
Social structure: Usually keep one; any group requires a much larger aquarium with separated nocturnal territories
Feeding and nutrition
Feeding ecology: Worms, crustaceans, insects, snails and accepted high-quality meaty prepared foods
Feeding routine: Feed at dusk or after lights dim; verify the fish feeds and adjust portions to body condition
Breeding, reproduction or spread
Cavity spawning and paternal guarding are reported for African knifefishes, but dependable species-specific home protocols for Xenomystus nigri remain limited
Detailed care and app-ready planning
- Identity scope
- Single-species profile for Xenomystus nigri. Preserve permanent AquaNexus ID 1258, slug african-knifefish and route species/african-knifefish/index.html; retain former combinations, locality labels and trade names only as searchable aliases.
- Adult size and space
- Expected adult size: Up to 30 cm standard length. Minimum permanent housing: At least 500 L with a 150 cm or longer footprint, deep dim refuge and unobstructed surface access. Plan around adult dimensions, activity, social structure, aggression, oxygen demand and waste production rather than sale size.
- Social structure
- Usually keep one; any group requires a much larger aquarium with separated nocturnal territories
- Swimming zone or placement
- Primary zone: Bottom and middle water; surface for air. Keep that zone usable for movement, feeding, refuge and escape.
- Feeding ecology
- Worms, crustaceans, insects, snails and accepted high-quality meaty prepared foods
- Feeding plan
- Feed at dusk or after lights dim; verify the fish feeds and adjust portions to body condition
- Water stability
- Maintain 22–28 °C; pH 6.0–8.0; hardness or minerals: 5–19 °dH (approximately 89–339 mg/L as CaCO₃); salinity: Freshwater; 0 ppt routine salinity. Stable oxygenation and nitrogen-cycle control matter more than chasing one exact value.
- Habitat structure
- Quiet, heavily structured aquarium with plants or wood, several dark refuges, gentle areas, strong biological filtration and a tight lid
- Compatibility plan
- Only with fish too large to swallow that will not attack it or monopolise nocturnal food and refuge
- Breeding or reproduction plan
- Cavity spawning and paternal guarding are reported for African knifefishes, but dependable species-specific home protocols for Xenomystus nigri remain limited Parental care: The male is reported to guard the clutch, but treat detailed aquarium claims cautiously unless a spawning is directly observed.
- Quarantine
- Quarantine new livestock in a separate cycled system for at least 30 days. Observe appetite, respiration, waste, skin, fins and behaviour; use dedicated equipment and never add transport water to the established aquarium.
- Welfare checks
- Maintain the stated adult space and social structure, verify feeding, and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. A 30 cm nocturnal predator can starve invisibly in a bright community. Small fish are prey and targeted dusk feeding is mandatory.
- Biosecurity and release
- Never release fish, fry, eggs, aquarium water, sediment, plants or live foods into drains, dams or natural waterways. Confirm current Australian import conditions and South Australian possession, trade and movement rules before acquisition or transfer.
- Main risk
- A 30 cm nocturnal predator can starve invisibly in a bright community. Small fish are prey and targeted dusk feeding is mandatory.
- Adult projected load
- Project biological load from the full adult african knifefish group, adult body mass, feeding pattern, activity and social requirement rather than juvenile sale size. Protein-rich dusk feeding and a 30 cm adult make the waste and oxygen demand substantial.
- Filtration
- Use mature biological filtration sized for the complete adult african knifefish group, with guarded intakes and accessible mechanical capture. Keep flow gentle to moderate in open areas while retaining calm dark refuges where the fish lives, and maintain undetectable ammonia and nitrite.
- Aeration
- Maintain reliable surface agitation and oxygen exchange at all times. Increase aeration during warm weather, medication, transport recovery, heavy feeding or any sign of rapid breathing.
- Maintenance
- Perform regular matched-water changes guided by nitrate and waste, remove uneaten food and trapped detritus, clean mechanical media without disrupting the biofilter, and record feeding, body condition, respiration and aggression.
- Overridable warnings
- Non-overridable: do not accept persistent ammonia or nitrite, oxygen distress, starvation, chronic aggression or inadequate adult space. Different equipment, stocking or maintenance methods may be used only when measured water quality and adult welfare remain equivalent or better. The fish must have dark refuge, targeted dusk feeding and unobstructed access to atmospheric air.
Compatibility, welfare and risk
Compatibility: Only with fish too large to swallow that will not attack it or monopolise nocturnal food and refuge
Welfare: Maintain the stated adult space and social structure, verify feeding, and intervene early when injury, exclusion, weight loss, abnormal respiration or altered behaviour appears. A 30 cm nocturnal predator can starve invisibly in a bright community. Small fish are prey and targeted dusk feeding is mandatory.
Main warning: A 30 cm nocturnal predator can starve invisibly in a bright community. Small fish are prey and targeted dusk feeding is mandatory.
Biosecurity and release
Never release fish, fry, eggs, aquarium water, sediment, plants or live foods into drains, dams or natural waterways. Confirm current Australian import conditions and South Australian possession, trade and movement rules before acquisition or transfer.