The Black Ghost Knife 22/27cm is a stunning, larger‑sized Black Ghost Knife Fish that makes an immediate impact in a big freshwater aquarium. With its jet‑black body, white markings on the tail and unique, undulating swimming motion, the Black Ghost Knife Fish looks like it’s gliding through the water rather than swimming.
This species, Apteronotus albifrons, comes from South America where it inhabits dimly lit rivers and streams. It’s a nocturnal, weakly electric fish that uses electric signals to navigate and locate food. Because of its size and sensitivity, the Black Ghost Knife 22/27cm is best kept by intermediate to advanced aquarists who can provide a suitably large, stable aquarium.
Size and Lifespan
- Current size: approximately 22–27cm
- Potential adult size: can reach around 40–50cm in a suitably large aquarium
- Lifespan: with good care, Black Ghost Knife Fish can live for many years
When you purchase a Black Ghost Knife 22/27cm, you’re getting a substantial fish that still has room to grow. Planning for its adult size and long‑term care is essential.
Black Ghost Knife 22/27cm – Tank Requirements
Because of their size and active swimming style, Black Ghost Knife Fish need a spacious aquarium:
- Recommended tank size: a large aquarium (4ft+ in length, bigger is better) for a single Black Ghost Knife 22/27cm, with more space as it approaches full size
- Filtration: strong, reliable filtration with good biological capacity and gentle flow in resting areas
- Décor: plenty of hiding places – caves, pipes, driftwood and plants help the fish feel secure
- Lighting: relatively dim or shaded areas, as the Black Ghost Knife Fish is naturally more active at night
Soft sand or smooth gravel is preferred so the fish doesn’t injure its delicate skin when exploring the bottom and squeezing into hides.
Water Parameters (Guide Only)
The Black Ghost Knife 22/27cm can adapt to a range of conditions if changes are slow and water quality is high:
- Temperature: around 24–27°C
- pH: roughly 6.5–7.5
- Hardness: soft to moderately hard water
- Ammonia & Nitrite: 0 ppm
- Nitrate: kept low with regular water changes
Stable, clean water is more important than chasing exact numbers. Avoid sudden swings in temperature, pH or hardness.
Feeding Black Ghost Knife Fish
The Black Ghost Knife 22/27cm is a carnivorous, nocturnal feeder that prefers meaty foods:
- Suitable foods:
- Frozen or live bloodworms
- Brine shrimp
- Blackworms
- Small prawns or shrimp pieces
- Quality sinking carnivore pellets or sticks
Feed your Black Ghost Knife Fish in the evening or when lights are dimmed, as they are more confident and active at night. Offer modest portions and remove uneaten food to maintain water quality.
Behaviour and Temperament
Black Ghost Knife Fish are generally peaceful towards other species, but can be territorial with their own kind in smaller tanks:
- Personality: shy to semi‑bold, often hiding during the day and exploring more at night
- Temperament: usually peaceful, but may become stressed or aggressive if crowded or kept with fin‑nippers
- Activity: glides along the bottom and mid‑levels, weaving in and out of décor
Providing enough hides and visual barriers helps your Black Ghost Knife 22/27cm feel secure and show more natural behaviour.
Tank Mates for Black Ghost Knife 22/27cm
Choose tank mates that are:
- Large enough not to be seen as food by a growing Black Ghost Knife Fish
- Peaceful to semi‑aggressive, but not persistent fin‑nippers
- Comfortable in similar water parameters and temperature
Avoid very small fish, aggressive fin‑nippers and other electric knife fish species in the same tank. Always consider the adult size of your Black Ghost Knife 22/27cm when planning long‑term stocking.
Important Notes
- Not suitable for small aquariums – this Black Ghost Knife 22/27cm will need a large tank as it grows.
- Sensitive to poor water quality – strong filtration and regular maintenance are essential.
- Provide plenty of hiding spots so your Black Ghost Knife Fish feels secure and settles in well.
