Siamese fighting fish
Betta splendens
Will it fit your tank?
Compare it with your tank's species, size, water tests and country.
Water
- Comfortable
- Acceptable, less ideal
- Tolerated, not comfortable
Space
Needs 20–41 L, depending on how it is kept
- The space it needs, from the least to the most generous
- Recommended
Character and care
- TemperamentUsually peaceful; can be aggressive, especially towards other males
- Social lifeIn groups
- DietOmnivore
- Water flowLow
Legal rules
The least the law allows, by country: the water and space above are what the species needs. A tank is checked against its own country's rules.
Austria
9 rules
- Temperature: 24–30 °C
- General hardness: 4–20 dGH
- pH 5.5–8.5
- Keep in harems, one male with several females
- Tank length at least 60 cm
- A tank of at least 54 L
- Ammonia: none
- Nitrite: none
- Nitrate: up to 50 mg/L NO₃
3 notes from the rules
Species-specific aggression (see the footnote on bettas)
For longer sales displays, a single male betta needs at least 1 L of water with a daily half water change, and protective decoration such as clumps of plants or bogwood.
Austria, general duties for freshwater fish: aim for middle values of the temperature, hardness and pH ranges; adjust new fish slowly to the water; change part of the water regularly, with water of the same quality; check temperature daily, and pH, hardness and nitrate at least every 14 days; check nitrite daily during the first six weeks of a new tank; give a clear day–night cycle; provide free swimming space, filter, heater and pump, substrate, hiding places and plants where the fish allow; keep the species according to its social structure; species kept together must suit each other in water quality, temperature and social behaviour (§ 7 (5); Anlage 5, 1.1).
Switzerland
5 rules
- At least 5.2 L of water per animal
- Tank length at least 21 cm
- Tank width at least 14 cm
- Tank height at least 7 cm
- Breeding restricted
Note from the rules
Switzerland, general duties for ornamental fish: minimum volume = each fish's current body length (snout to tail base) × litres per cm by size class (up to 5 cm 0.5; 10 cm 0.75; 15 cm 1; 20 cm 1.25; 30 cm 1.75; 40 cm 2.25; over 40 cm 3), summed over all fish, plus species-specific needs; the tank at least 3 times as long and 2 times as wide as the largest fish's body length, and the water at least that deep; not visible from all sides, with visual cover and retreats; a day–night rhythm; water quality suited to the species; no prolonged strong vibration; social species need contact with their own kind; prevent excessive breeding; genetically modified fish such as GloFish are banned (TSchV Art. 13, 25, 98 and Anhang 2 Tabelle 8).