Guppy tank size
A 10 gallon suits a small group of 5; a 20 gallon long holds 10 or more and meets the recommended footprint.
Guppies are about 2.4 inches as adults and live in loose groups, so there is no fixed school size. Seriously Fish gives a base of 45 x 30 cm (about 18 x 12 inches). A 5 gallon is under it and a 10 gallon is close; the 15 gallon and 20 gallon long meet it comfortably. Keep two or three females per male, and remember that a mixed group breeds every month, so leave room to grow.
How many guppies fit in each tank
Counts are for a tank with nothing else in it, from the same model as the stocking calculator.
| Tank | Length x width | Meets the footprint | Most on their own |
|---|---|---|---|
| 5 Gallon | 16 x 8 in | Under | up to 3 * |
| 10 Gallon | 20 x 10 in | Close | up to 5 * |
| 15 Gallon | 24 x 12 in | Yes | up to 8 |
| 20 Gallon Long | 30 x 12 in | Yes | up to 10 |
| 20 Gallon High | 24 x 12 in | Yes | up to 11 |
| 29 Gallon | 30 x 12 in | Yes | up to 15 |
| 40 Gallon Breeder | 36 x 18 in | Yes | up to 25 |
| 55 Gallon | 48 x 13 in | Yes | up to 32 |
| 75 Gallon | 48 x 18 in | Yes | up to 44 |
| 125 Gallon | 72 x 18 in | Yes | up to 69 |
Footprint is the Seriously Fish minimum base of 18 x 12 in. “Close” is within 20%. * Fits by volume, but the footprint is under the recommendation.
The smallest tank that meets the footprint
15 Gallon: 24 x 12 x 12 inches.
Guppy at a glance
| Adult size | about 2.4 in |
|---|---|
| Minimum base | 18 x 12 in |
| Temperature | 63 to 82°F |
| pH | 7.0 to 8.5 |
| Group | loose groups, no minimum |
Tank mates
Guppies are very peaceful. Keep them with other calm fish and away from fin nippers such as tiger barbs and serpae tetras. Do not mix them with Endler's livebearers, which crossbreed.
Seriously Fish: Very peaceful; suits quiet community tanks. Do not keep with fin-nipping species such as tiger barbs or serpae tetras.
Mixes with guppies that pass the check
- 10 Gallon: a few guppies68% stocked
4 × Guppy.
- 29 Gallon: guppies with a bristlenose pleco79% stocked
8 × Guppy, 1 × Bristlenose pleco.
Common questions
What size tank does a guppy need?
Seriously Fish gives a minimum base of 45 x 30 cm, about 18 x 12 in. The smallest standard tank that meets it is the 15 gallon.
What temperature and pH do guppies need?
63 to 82°F and a pH of 7.0 to 8.5, by Seriously Fish.
How big do guppies get?
About 2.4 inches (60 mm) as adults, by Seriously Fish.
How many guppies can I keep in a 5 gallon tank?
Three on their own, by our calculator, and the tank is under the footprint Seriously Fish recommends. A 10 gallon is a better minimum.
Do guppies need a heater?
Usually. They accept 63 to 82°F, so an unheated room that stays above 65°F is fine, but most homes need a small heater for a stable temperature.
Gear for a guppy tank
Searches on Amazon for the right size. Check the tank size or flow rating on the listing before you buy.
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Sources: Seriously Fish. Scientific name Poecilia reticulata.