Betta fish care: a complete beginner's guide (Betta splendens)

The betta (Betta splendens), also called the Siamese fighting fish, is the world's best-selling aquarium fish and also its most mythologised one. Pet shops often keep them in 200–300 ml cups, which has bred the persistent belief that 'a betta can live in any jar'. In reality, the betta is a tropical fish from the warm rice fields of Southeast Asia and it needs heat, filtration and proper volume. This guide gives realistic requirements, concrete numbers and the pitfalls to avoid.

Tank size and shape

Minimum for one betta — 19 L (5 US gal). Optimum — 38 L (10 US gal). At that volume parameters stay stable, you can plant the tank and run a proper filter. The lid is non-negotiable: bettas are jumpers.

Long and low is better than tall and narrow: the betta breathes atmospheric air through a labyrinth organ and surfaces regularly. Tall bowls and bubble vases exhaust the fish through endless trips up and down.

Water parameters

Temperature: 24–27 °C (75–80 °F). A heater is mandatory — without it winter temperatures drop to 18 °C / 64 °F, which suppresses immunity and triggers ich. pH 6.5–7.5. gH 5–15. Ammonia and nitrite: 0. Nitrate: up to 20 mg/L. Weekly 25% water changes with dechlorinator.

Filter and flow

A filter is required — otherwise the biofilter can't keep up with waste. But flow needs to be MINIMAL: long-finned bettas act like sails in fast currents and tire out. Best picks are an air-lift sponge filter or a small internal filter with the flow regulator on minimum. More on this in our [filters and aeration guide].

Feeding

Bettas are carnivores. Base their diet on high-protein betta pellets (Hikari Betta, Sera Betta). Two pellets, 1–2 times a day. Once a week — frozen bloodworms or brine shrimp. Once a week — a fast day, otherwise constipation and swim-bladder issues follow (especially in fancy short-bodied lines). Do NOT feed generic tropical flakes — too low in protein and prone to causing digestive issues.

Tankmates

A male betta lives ALONE. Two males in the same tank means a guaranteed fight to the death. Possible tankmates: Neocaridina shrimp (though juveniles will be eaten), apple snails, small bottom catfish (otocinclus, panda corydoras) in a tank of at least 38 L. NOT compatible: guppies (the betta will shred their tails), nippy tetras (serpae, black skirts), anything else with long fins.

Females can live in a group of 5+ in a tank of 60 L or more — that's called a 'sorority'. The hierarchy is harsh, so plenty of hides and dense planting are needed for weaker individuals to retreat.

Common diseases and prevention

The classic betta problems: fin rot (poor water), saprolegnia on wounds from jumps and fights, ich in cold water, swim-bladder disorder from overfeeding. Prevention is simple: stable warm water, varied food without overdoing it, minimum stress, quarantine for new fish. Details in our [fish diseases handbook].

Breeding

The male builds a bubble nest at the surface and the eggs go into it after spawning. Fry hatch in about 2 days. The female has to be removed immediately after spawning — the male will kill her. Fry start on infusoria, then move to baby brine shrimp. Breeding needs a 20–40 L grow-out tank and experience — not a first-aquarium project.

A betta is an excellent first fish if you treat it like a real pet: warm water, decent volume, sensible food. A jar of tap water is not an option.

Lifespan

In proper conditions a betta lives 3–5 years, with records up to 7. In a cup of unfiltered cold water the average lifespan is 6–12 months. Buy fish that are at least 3 months old (younger ones travel poorly), and check fins and belly for disease signs before purchase.