What size tank does a Jack Dempsey need?
At least 55 gallons (208 liters). The smallest standard tank that works is the 55 gallon. A bigger tank is always easier to keep stable. We give the size for an adult fish, because the small fish in the shop will grow. Scientific name: Rocio octofasciata.
How many Jack Dempseys in each tank size?
This is how many each standard tank carries comfortably if Jack Dempseys are the only fish in it. Share the tank with other species and the number goes down.
| Tank | How many Jack Dempseys |
|---|---|
| 5 gallon | Too small |
| 10 gallon | Too small |
| 20 gallon long | Too small |
| 29 gallon | Too small |
| 40 gallon breeder | Too small |
| 55 gallon | 1 |
| 75 gallon | 1 |
| 125 gallon | up to 2 |
Check Jack Dempseys against your own tank and other fish
Good to know
- It eats fish small enough to swallow. Choose tankmates at least half its length.
Tank mates for Jack Dempseys
These animals like the same water, are a safe size, and have a temper that fits. It is a match on paper: always watch new tankmates for the first week.
Poor matches
- Betta: Jack Dempsey (about 8 in) can eat betta (about 2.6 in).
- Guppy: Jack Dempsey is aggressive and will bully or kill peaceful fish such as guppy.
- Fancy goldfish: Goldfish do best with other fancy goldfish.
Questions and answers
What size tank does a Jack Dempsey need?
At least 55 gallons (208 liters). The smallest standard tank that works is the 55 gallon. A bigger tank is always easier to keep stable.
How many Jack Dempseys should be kept together?
One is fine. A Jack Dempsey does not need company, though a large enough tank can hold more than one.
Can Jack Dempseys live in a 10 gallon tank?
No. Jack Dempsey needs at least 55 gallons (208 liters), and grows to 8 in (20 cm), far too long for a 20 inch tank.
What temperature do Jack Dempseys need?
72–82 °F (22–28 °C), with a pH of 6.5–8. In most homes that means a heater.
Can Jack Dempseys live with a betta?
It is not a good match. Jack Dempsey (about 8 in) can eat betta (about 2.6 in).
More fish
Adult size, tank size and water ranges follow the mainstream care consensus (Seriously Fish species profiles and FishBase maximum lengths). Where sources differ we use the more cautious figure. Stocking numbers come from our stocking calculator.