Can a betta live with fancy goldfish?
Edited by Marin Hale · last reviewed October 29, 2026
No.
Fancy goldfish need cool water; betta fish need tropical water.
Why it doesn’t work
Fancy goldfish do best in cool water, 65–74°F, while bettas need tropical water at 75–82°F. There is no temperature that suits both. Keep it cool and the betta gets chilled and stressed, which weakens its immunity. Keep it warm and the goldfish runs too hot and is stressed. The other checks (pH, hardness, size, fins, temperament) are fine, but they can't make up for a temperature gap that neither fish can live with long-term.
If they’re already together
- Set up a separate tank for one of the fish, ideally at least 20 gallons for the goldfish, and move that fish over as soon as you can.
- Until then, don't try to split the difference with the heater. Accept that one fish is uncomfortable, and watch the betta for lethargy or clamped fins and the goldfish for stress.
- Keep up regular water testing and changes during the move. Fancy goldfish are the larger fish, so the established tank usually works best for them, and the betta can go in a new, properly cycled tank.
Instead: House each fish on its own: fancy goldfish in a cool tank of at least 20 gallons, and the betta alone in a heated tank at 75–82°F. Both species do best in a mature, cycled tank, so set up and cycle the second tank before moving anyone.
How we reached this verdict
| Problem | Water temperature | Fancy goldfish need cool water; betta fish need tropical water. |
|---|---|---|
| Pass | pH | Both are comfortable at pH 6.8–7.5. |
| Pass | Water hardness | Both handle water hardness of 8–15 dGH. |
| Pass | Size and appetite | Neither is small enough to be eaten by the other. |
| Pass | Fins | No fin-nipping risk. |
| Pass | Temperament | Temperaments are compatible. |
Side by side
| Trait | Betta fish | Fancy goldfish |
|---|---|---|
| Tolerates | 75–82°F (24–28°C) | 65–74°F (18–23°C) |
| pH | 6–7.5 | 6.8–8.4 |
| Adult size | 2.5–2.8 in | 6–8 in |
| Temperament | Semi-aggressive | Peaceful |
| Smallest tank | 5 gallons (19 L) | 20 gallons (76 L) |
| Keep at least | 1 (fine alone) | — |
| Swims | Top | Bottom |
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Verdicts come from cross-checked species data and our compatibility rules. How verdicts work · Fancy goldfish care