Black Ghost Knifefish: Care, Facts & Setup Guide

Meet the Black Ghost Knifefish (Apteronotus albifrons)—a sleek, midnight swimmer that ripples a ribbon-like fin to glide forward or backward. Native to river systems from Venezuela through the Amazon and down into the Paraguay–Paraná basin, this oddball is famous for its “sixth sense”: a gentle electric field it uses to navigate and find food.

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Quick Facts

Scientific name	Apteronotus albifrons
Origin	Northern–southern South America (Amazon & Paraguay–Paraná drainages)
Adult size	Up to ~20 in / 50 cm (plan tank accordingly)
Temperament	Shy, nocturnal; peaceful with appropriately sized tankmates
Experience level	Intermediate–advanced (size & sensitivity)

Why “Ghost”? And what’s with the electricity?

In low-light, tannin-stained waters, knifefish move almost silently—hence the “ghost.” They also generate a steady, weak electric field and sense distortions with specialized skin receptors. When two knifefish with similar frequencies meet, each shifts its frequency slightly—a classic behavior called the Jamming Avoidance Response—so their “signals” don’t interfere.

Care & Setup

Tank size & aquascape

• Go long: A large footprint is key for an adult—think 100+ gallons for a single fish (many experienced keepers prefer 120–180 gallons).
• Layout: Provide caves (PVC/ceramic tubes, rock piles), driftwood, and dense plants for daytime hiding. Fine sand or very smooth gravel protects their delicate skin.
• Lighting/flow: Subdued lighting with gentle–moderate flow and strong, stable filtration.

Water parameters

• Temperature: 75–82°F (24–28°C)
• pH: ~6.5–7.5 (slightly soft to neutral works well)
• Quality: Ammonia/nitrite 0; keep nitrate low via regular water changes. Knifefish are sensitive to poor water and big swings—aim for consistency.

Diet

Carnivorous. Offer varied frozen or live foods (bloodworms, blackworms, brine shrimp, chopped earthworms) and high-quality sinking carnivore pellets. Feed after lights-out at first; many learn to eat in daytime and even hand-feed.

Tankmates

Choose peaceful, non-nippy companions that are too large to be a snack (e.g., silver dollars, larger peaceful tetras/rasboras, calm cichlids). Avoid fin-nippers and other knifefish unless you have a very large, carefully planned setup.

Health notes

Knifefish are effectively scaleless/reduced-scale and can be sensitive to medications (especially copper). Quarantine new fish, maintain strong oxygenation, and prioritize clean, stable water over heavy medicating.

Fun Bits to Share

• They can swim forward or backward by reversing the undulation of their long anal fin.
• The Jamming Avoidance Response made knifefish a model in neuroethology—helping scientists map how brains compute sensory information.

Ready to add a “ghost” to your tank?

With the right space and care, the Black Ghost Knifefish is a mesmerizing, personable showpiece for a peaceful community.