Diamond Tetra: Tank Size, Tank Mates & How Many to Keep

What size tank do diamond tetras need?

At least 20 gallons (76 liters) for a group of 6. The smallest standard tank that works is the 20 gallon high. A bigger tank is always easier to keep stable. We give the size for an adult fish in a proper group, because the small fish in the shop will grow. Scientific name: Moenkhausia pittieri.

How many diamond tetras in each tank size?

This is how many each standard tank carries comfortably if diamond tetras are the only fish in it. Share the tank with other species and the number goes down.

Tank	How many diamond tetras
5 gallon	Too small
10 gallon	Too small
20 gallon long	up to 7
29 gallon	up to 11
40 gallon breeder	up to 15
55 gallon	up to 21
75 gallon	up to 28
125 gallon	up to 47

Check diamond tetras against your own tank and other fish

Good to know

Keep at least 6. Alone or in twos and threes, diamond tetras hide, stop eating well, or pick on each other.

Tank mates for diamond tetras

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

Guppy: They need different water: Diamond tetra likes a pH of 5.5–7, guppy likes 7–8.2.
Fancy goldfish: Goldfish do best with other fancy goldfish.
Oscar: Oscar is aggressive and will bully or kill peaceful fish such as diamond tetra.
Molly: These fish do not share a comfortable pH range. Choose fish from similar water.

Questions and answers

What size tank do diamond tetras need?

At least 20 gallons (76 liters) for a group of 6. The smallest standard tank that works is the 20 gallon high. A bigger tank is always easier to keep stable.

How many diamond tetras should be kept together?

At least 6. Diamond tetras are social animals and only behave naturally in a group. More is better if the tank has room.

Can diamond tetras live in a 10 gallon tank?

No. Diamond tetra needs at least 20 gallons (76 liters).

What temperature do diamond tetras need?

75–82 °F (24–28 °C), with a pH of 5.5–7. In most homes that means a heater.

Can diamond tetras live with a betta?

Usually, yes, in a tank of 20 gallons (76 liters) or more. They like the same water: 75–82 °F (24–28 °C). Every betta has its own temper, so watch closely for the first week and have a spare tank ready.

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.