What fish can live with Black Ghost Knife?

Black Ghost Knife pairs well with Cardinal Tetra, Rummynose Tetra, Harlequin Rasbora, Fancy Guppy, Platy, Molly. Compatibility depends on tank size, water parameters, and stocking density; the full list on this page ranks every checked pairing.

Species Profile

Black Ghost Knife

Apteronotus albifrons

Also known as: BGK, Black Ghost

Oddballspeaceful

Adult size

18″

Minimum tank

100 gal

Temperature

75–82°F

6.5–7.5

Schooling

Solitary OK

Water level

bottom

Grows from juvenile

Typically sold at ~4″ and reaches 18″ over ~2 years. Plan tank size for the adult, not the fish at purchase.

Diet

Frozen bloodworms, mysis, krill, eats anything small enough

Notes

Solid black eel-shaped electric fish, generates a weak electric field to navigate. Nocturnal. Peaceful with similar-sized tankmates but will eat any fish small enough to swallow. Needs a hiding tube and dim lighting.

Compatible Tankmates

Best tank mates for Black Ghost Knife

Every species below passes the compatibility engine when paired with Black Ghost Knifein a suitably sized tank. Verdicts come from the same rules the builder uses — click a card to see that species' own care profile and its tank mates in turn.