How big does Betta get?

Betta reaches an adult standard length of 5–6.5 cm (excluding the caudal fin). Size the tank for that, not for the juvenile you bring home — the difference is often several times over, and upgrading later costs more than buying once.

What water does Betta need?

24–30 °C, pH 6–7.5, 2–12 dGH, 0–8 dKH. At 6 °C wide it is one of the more forgiving ranges.

What is the smallest tank for Betta?

At least 20 L, and no shorter than 40 cm. That is the floor for long-term keeping, not for short-term survival: volume buys water stability and length buys swimming room, and neither substitutes for the other. It is not a schooling fish, so a single specimen or a pair is fine.

What is Betta like to keep?

Temperament: semi-aggressive. Difficulty: beginner. It occupies the top and is carnivore. With plants it is "Leaves plants alone".

Can Betta be kept with its most common tank mate?

The checker returns "Can be kept together". Betta and Peppered Cory is a well-established pairing. Individual fish still differ; the record says "usually fine", not "guaranteed".

G-01 / 05Freshwater

Betta泰国斗鱼

Betta splendens · Osphronemidae

A labyrinth fish for a single-fish 20 L filtered tank; two males must never share it.

Illustration to come

G-01 / 05 · Betta Betta splendens

SpecificationsFish atlas

Name: 泰国斗鱼
Scientific name: Betta splendens
Family: Osphronemidae
Origin: Southeast Asia (Thailand, Cambodia, Vietnam)
Adult size: 5–6.5 cm
Temperament: Semi-aggressive
Diet: Carnivore
Water level: Top
Level: Beginner
Min. tank: 20 L
Min. length: 40 cm
Plant safe: Leaves plants alone

Water requirementsFreshwater

Temp.24–30 °C

pH6–7.5

Hardness2–12 dGH

Alkalinity0–8 dKH

Units: temperature in °C, hardness in German degrees (dGH / dKH), marine salinity as specific gravity at 25 °C, volume in litres. These are the values recorded for the species and do not follow the site unit switcher.

Keeping notes

1House alone or with peaceful bottom dwellers; two males in one tank fight until one dies.
2Needs a steady 26-28 °C and weekly water changes, never an unfiltered jar with no changes.
3Carnivorous on betta pellets and frozen bloodworm, with leftovers siphoned out at once.
4Its labyrinth organ breathes air, so leave surface access and avoid strong current or sharp decor that tears fins.

Check a tank mate

Jump straight to the verdict for Betta against this one — no need to pick it again.

Frequently asked questions

How big does Betta get?: Betta reaches an adult standard length of 5–6.5 cm (excluding the caudal fin). Size the tank for that, not for the juvenile you bring home — the difference is often several times over, and upgrading later costs more than buying once.
What water does Betta need?: 24–30 °C, pH 6–7.5, 2–12 dGH, 0–8 dKH. At 6 °C wide it is one of the more forgiving ranges.
What is the smallest tank for Betta?: At least 20 L, and no shorter than 40 cm. That is the floor for long-term keeping, not for short-term survival: volume buys water stability and length buys swimming room, and neither substitutes for the other. It is not a schooling fish, so a single specimen or a pair is fine.
What is Betta like to keep?: Temperament: semi-aggressive. Difficulty: beginner. It occupies the top and is carnivore. With plants it is "Leaves plants alone".
Can Betta be kept with its most common tank mate?: The checker returns "Can be kept together". Betta and Peppered Cory is a well-established pairing. Individual fish still differ; the record says "usually fine", not "guaranteed".