Koi Betta
Betta splendens
The Koi Betta (Betta splendens) is a semi-aggressive fish that's a good step up once you have a little experience. Give it a tank of at least 40 litres (11 US gallons), water held at 72-86°F, and a pH of 6-7.5.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
Southeast Asia
- East & Southeast Asia
Regional colours match the stocking calculator's origin map.
Koi Betta Tank Setup
A single male is happiest in at least 40 litres (11 US gallons), heated to 72-86°F, with a pH around 6-7.5. Give him a calm water surface to breathe at, and fit a lid - bettas can jump.
What Do Koi Bettas Eat?
They have small mouths, so stick to small foods: crushed flake, fine granules, and now and then a treat of frozen or live foods such as daphnia or baby brine shrimp. Anything too large simply gets ignored.
Koi Betta Tank Mates
Predatory; may eat small fish or inverts. Males must be kept alone; females may cohabit in spacious tanks with cover. The Koi Betta is semi-aggressive, which is the first thing to weigh up when you choose tank mates. It's predatory, so anything small enough to fit in its mouth will be treated as food rather than a companion. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Koi Bettas Good for Beginners?
Not a sensible first purchase. Get the tank cycled, keep easier fish stable for a year, then revisit if you still want the extra work this species demands.
Koi Betta - frequently asked questions
What size tank do Koi Bettas need?
Koi Bettas need a tank of at least 40 litres (11 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
What water parameters do Koi Bettas need?
Keep them at 72-86°F with a pH of 6-7.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Koi Bettas eat?
Koi Bettas have small mouths, so they need small foods. Crushed flake and fine granules form the staple, with the occasional treat of frozen or live foods such as daphnia or baby brine shrimp. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Koi Bettas good for beginners?
Koi Bettas are best for keepers with a little experience. They are manageable once you test water regularly and catch problems early; a complete beginner may prefer something more forgiving first.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Koi Bettas
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- Pea PufferPredator - Pea Puffer will eat or injure smaller tank mates
- Plakat BettaPredator - Plakat Betta will eat or injure smaller tank mates
