Common name
Black ghost knifefish
Scientific name
Apteronotus albifrons
Category
Freshwater fish
Group
Knifefishes
Environment
Very large mature freshwater aquarium with subdued light, high oxygen, current, soft sand and full-body shelters
Origin
South America from Venezuela through the Amazon basin to the Paraguay and Paraná river systems
Care level
Advanced specialist
Adult size
Up to 50 cm total length
Expected lifespan
No dependable species-specific captive maximum was located; plan for well over a decade of adult-scale care.
Minimum housing
At least 750 L with a 180 cm or longer length and at least 60 cm front-to-back turning room for one adult
Temperature
23–28 °C
pH
6.0–8.0
Hardness / minerals
5–19 dGH
Salinity
Freshwater, 0 ppt; routine salt addition is not recommended
Lighting
Subdued, with complete dark shelters available during the day
Placement / zone
Bottom and lower water by day; broader water-column use after dark
Filtration
Use mature biological filtration sized for the complete adult black ghost knifefish group, with guarded intakes and accessible mechanical capture. Keep flow moderate with strong whole-system oxygen, long open movement lanes and protected low-light 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 Apteronotus albifrons. Similar black ghost knifefishes occur, so white tail-band pattern and reliable provenance should be checked.

Search names: Black ghost, Black ghost knife fish

Environment and housing

Use soft sand, smooth wood and rock, several long opaque tubes or caves, strong filtration, moderate current, high oxygen and a secure lid

Social structure: Keep one adult; conspecifics and other electric knifefishes require exceptional space and careful monitoring

Feeding and nutrition

Feeding ecology: Nocturnal micropredator taking insect larvae, worms, crustaceans and small fishes; many individuals can be trained to frozen and sinking prepared foods

Feeding routine: Feed one or two measured evening meals and verify the fish locates and consumes food without hand-feeding dependence

Breeding, reproduction or spread

Egg-laying and captive spawning have been reported, but sexing, triggers and larval rearing remain specialist and are not dependable for routine home aquaria

Detailed care and app-ready planning

Identity scope
Single-species profile for Apteronotus albifrons. Similar black ghost knifefishes occur, so white tail-band pattern and reliable provenance should be checked.
Adult size and space
Adults reach 50 cm total length. Use at least 750 L with 180 cm or more of length and 60 cm or more front-to-back so the fish can turn without bending against glass or décor.
Social structure
Keep one adult as the standard plan. Electrical communication and territorial interactions can cause chronic conflict between conspecifics or similar knifefishes in ordinary aquariums.
Swimming zone or placement
Shelters near the bottom during bright periods and forages more broadly after dark using an undulating anal fin and electrosensory system.
Feeding ecology
A nocturnal micro-predator of insect larvae and other small animals, locating prey in darkness with weak electric sensing.
Feeding plan
Offer varied frozen or thawed invertebrate foods and suitable sinking carnivore pellets after lights dim. Avoid conditioning the fish to take food only from a hand.
Water stability
Maintain 23–28 °C, pH 6.0–8.0 and 5–19 dGH with high dissolved oxygen, zero ammonia and nitrite and low nitrate.
Habitat structure
Provide soft sand, smooth hardscape, several opaque full-body shelters, moderate flow, protected heaters and pumps, and a secure cover.
Compatibility plan
Choose peaceful fish too large to swallow that use open middle or upper water. Avoid tiny fish, aggressive cichlids, fin-nippers and other electric knifefishes.
Breeding or reproduction plan
Captive spawning is possible but specialist. Do not present a universal sexing method or breeding trigger; use documented broodstock and separate larval systems only under experienced management.
Quarantine
Quarantine in a separate cycled freshwater aquarium with dedicated nets, containers and siphons. Match temperature and mineral chemistry gradually, confirm normal feeding, respiration, skin, fins and waste, and never pour transport water into the established aquarium.
Welfare checks
Check weight, snout and skin condition, respiration, normal reverse and forward swimming, shelter access, nighttime feeding and clearance for turning.
Biosecurity and release
Never release fish, fry, eggs, aquarium water, sediment, plants or foods into drains, dams or natural waterways. Check the exact accepted scientific name in current BICON and applicable South Australian rules before import, sale or movement; import eligibility does not authorise release or wild collection.
Main risk
The main failure is buying a small juvenile without permanent space for a 50 cm adult, leading to restricted turning, injury and chronic stress.
Adult projected load
Project biological load from the full adult black ghost knifefish group, adult body mass, feeding pattern, activity and social requirement rather than juvenile sale size. A 50 cm predatory knifefish creates a very high protein, biomass and oxygen load, and hidden feeding makes waste and weight loss easy to miss.
Filtration
Use mature biological filtration sized for the complete adult black ghost knifefish group, with guarded intakes and accessible mechanical capture. Keep flow moderate with strong whole-system oxygen, long open movement lanes and protected low-light 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 750 L, 180 cm-long adult system, turning width, secure cover and confirmed feeding cannot be reduced because the fish is a juvenile.

Compatibility, welfare and risk

Compatibility: Use peaceful larger fish that cannot be swallowed and do not occupy the same dark shelters; avoid fin-nippers and other electric knifefishes

Welfare: Check body condition, snout and skin, respiration, shelter use, nighttime activity and turning clearance; unexplained pacing or refusal to leave cover can indicate a major environmental problem.

Main warning: Juveniles are commonly sold for aquariums far too small for a 50 cm adult. A narrow tank also prevents this relatively stiff-bodied fish from turning safely.

Biosecurity and release

Never release fish, fry, eggs, aquarium water, sediment, plants or foods into drains, dams or natural waterways. Check the exact accepted scientific name in current BICON and applicable South Australian rules before import, sale or movement; import eligibility does not authorise release or wild collection.

Sources