Can bettas live with black ghost knives?
Verdict
No
No. Bettas and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 2.5 inches bettas do.
What to watch
- Deal breakerAn adult black ghost knife eats fish that fit in its mouth, and at 2.5 inches bettas do.
- Watch outBlack ghost knives are much bigger and pushier than bettas, which are slow and easy to bully at feeding time.
- Watch outBlack ghost knives grow to 15 inches and need 125 gallons, far more than a tank set up for bettas.
What works
- Both are fine at 76–82°F.
- pH 6.5–7.5 suits both.
- They use different parts of the tank: bettas the top, black ghost knives the bottom.
Water side by side
Size to scale
Care at a glance
| Betta | Black ghost knife | |
|---|---|---|
| Temperature | 76–82 °F | 73–82 °F |
| pH | 6.5–7.5 | 6–8 |
| Adult size | 2.5 in | 15.0 in |
| Minimum tank | 5 gal | 125 gal |
| Temperament | Semi-aggressive | Semi-aggressive |
| Swims at | Top | Bottom |
| Group | One per tank | One per tank |
| Diet | Carnivore | Carnivore |
Better tank mates for bettas
Better tank mates for black ghost knives
All black ghost knife tank mates
Questions
Can bettas live with black ghost knives?
No. Bettas and black ghost knives should not share a tank. An adult black ghost knife eats fish that fit in its mouth, and at 2.5 inches bettas do.
What temperature suits both bettas and black ghost knives?
76–82 °F. Bettas need 76–82 °F, black ghost knives need 73–82 °F.
What size tank do bettas and black ghost knives need together?
At least 125 gal, set by the black ghost knife. Add space for each extra fish.