Compatibility brief
Can Black ghost knifefish live with Congo Tetra?
Caution. Check the issues below before buying.
Compatibility score
Profile confidence: low
Order of checkstank volume vs adults → predation mouth gap → temperament / fin nipping → shared water windows.
500L
Combined minimum footprint reference for these two species: about 500L (larger active fish often want more length).
Black ghost knifefish (45cm adult) may treat small Congo Tetra (~8cm) as food once grown — plan adult sizes, not shop sizes.
Black ghost knifefish is a fin nipper and Congo Tetra is vulnerable to nipping — long fins are a common target even when water parameters match.
Assessment details
Temperament difference
Top issueBlack ghost knifefish is semi-aggressive, while Congo Tetra is peaceful. Expect chasing or stress unless the tank is large and heavily structured — monitor closely.
Fin nipping risk
Black ghost knifefish is a known fin nipper and Congo Tetra has long, flowing fins. Black ghost knifefish will likely harass Congo Tetra.
Compatible temperature range
Both fish can comfortably share similar water temperatures.
“Black ghost knifefish is semi-aggressive, while Congo Tetra…”
Temperament difference
Next steps
Concrete changes, not "research more" filler.
- •Provide plenty of hiding spots and visual breaks so Congo Tetra can escape if harassed.
- •Avoid keeping Black ghost knifefish with long-finned fish like Congo Tetra.
- •Congo Tetra should be kept in a group of at least 8 for best health and behaviour.
- •Black ghost knifefish reaches ~45cm: tank length and turning room matter more than the litre number. A tall, short tank of the same volume is not equivalent.
- LiveAquaria. Black ghost knifefish (Apteronotus albifrons care sheet)
Primary: large-aquarium retailer care profile: very large tank, dim lighting, hiding, carnivore diet, and size expectations. Cross-check the stated minimum with your own footprint and filtration; Fishori uses a stricter home-aquarium minimum than a catalog line.
- FishBase. Apteronotus albifrons
Secondary: natural history and max length; weakly electric foraging in the dark. Translate into tank length and nocturnal feeding, not a neon-tetra list.
- Seriously Fish. Phenacogrammus interruptus
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Phenacogrammus interruptus
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Phenacogrammus interruptus
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Try this next
Build the full stocking list with Black ghost knifefish + Congo Tetra
Plan further
Check each species’ mates list, size the glass, then verify the full stock in the builder. Methodology explains how verdicts are produced.
Individual fish vary in personality. Fishori uses conservative hobby rules. Observe any new introduction closely, feed thoughtfully, and keep a quarantine or backup plan. This is not veterinary advice.
Profile data confidence: medium. Driven by the lower-confidence profile (Black ghost knifefish): Typical care sources — real tanks still vary.