Species · Bettas & gouramis
Betta
Betta splendens
A tropical labyrinth fish that needs a heated, filtered, cycled tank — never a bowl or vase. Get the warm, gently-filtered water right and a betta is a hardy, characterful, long-lived pet.
Difficulty: BeginnerNano / betta tank✓ Fact-checked care guide
Quick facts
| Adult size | ~7 cm / 2.8 in body (plus flowing fins) |
|---|---|
| Minimum tank | 19 L / 5 US gal minimum for one betta — ~40 L / 11 US gal is better |
| Temperature | 24–27 °C / 75–81 °F (within the species range of 22–30 °C / 72–86 °F) |
| pH | 6.0–8.0 (ornamental strains are unfussy) |
| Hardness | 1–15 dGH (soft to moderately hard) |
| Filtration & flow | Cycled, gentle filtration (a sponge filter is ideal) — this species hates strong flow |
| Diet | Carnivore / insectivore — a betta-specific pellet base plus regular small live/frozen foods |
| Social | Solitary. House one betta per tank; two males will fight, often fatally |
| Temperament | Bold and curious, but a solitary specialist — not a peaceful community fish |
| Lifespan | 3–5 years with good care |
Overview
The betta (Betta splendens, the Siamese fighting fish) is the single most popular fish in the hobby — and the most often mis-sold. It has been line-bred for centuries into the flowing-finned, jewel-toned forms sold today. That heritage is exactly why the bowl is a myth: this is a tropical freshwater fish, not a novelty ornament.
Bettas are labyrinth fish — they have an accessory breathing organ that lets them gulp air from the surface, which is how they survive in warm, oxygen-poor water in the wild. People wrongly take this to mean "it can live anywhere". It cannot: it still needs warm, clean, stable, cycled water. Get that right and a betta is genuinely hardy, interactive, and easy — one of the best first fish there is.
Water & tank
Warm, stable, cycled water is the whole game. A betta needs a heater holding 24–27 °C / 75–81 °F and a filter running through a completed nitrogen cycle before the fish goes in. Unheated room-temperature water and "just add water" bowls are the two most common reasons a betta declines.
Give it at least 19 L / 5 US gal — SeriouslyFish recommends a tank with a 45 × 30 cm / 18 × 12 in base (about 40 L / 11 US gal) as the sensible home for a single betta, and explicitly does not support keeping them in tiny jars or vases. More water is easier to keep stable, not harder.
Keep the flow gentle — a betta's long fins tire in strong current, so an air-driven sponge filter suits it perfectly. Plant it heavily (real or silk; hard plastic tears fins), give it surface cover and shady spots, keep a lid on (bettas are excellent jumpers), and leave an air gap above the water so it can reach the surface to breathe.
Feeding
A betta is a carnivore, not a flake-and-forget fish. Base the diet on a good betta-specific pellet, and offer small live or frozen foods — daphnia, artemia (brine shrimp), or bloodworm — regularly for colour and condition.
Feed small amounts once or twice a day and do not overfeed: bettas are particularly prone to obesity and to bloating/constipation. A day off food each week is fine and often helps digestion.
Behaviour & tankmates
The name says it: males will fight other males, often to the death, and will also flare at and shred their own reflection or long-finned tankmates. Keep one betta to a tank as the safe default.
A betta is best thought of as a species-tank centrepiece, not a community fish. Some peaceful, non-nippy tankmates (and the classic snail/shrimp cleanup crew) can work in a larger, well-planted tank — but it is individual and never guaranteed, so always have a backup plan to separate. "Sororities" of females are advanced and frequently go wrong; they are not a beginner project.
What to expect
A settled betta is curious and interactive — it will learn feeding time and come to the glass. In the first days a new betta may be shy, clamp its fins, or explore cautiously; give it calm, warm, stable water and time.
Watch the fins and colour: bright colour, open flowing fins, and a healthy appetite are your day-to-day "all is well" signs.
Myths, kindly busted
“Bettas live happily in bowls or vases because they breathe air.”
The labyrinth organ lets a betta survive low-oxygen water — it does not remove the need for a heated, filtered, cycled tank. SeriouslyFish explicitly does not support keeping them in tiny jars or bowls.
“A betta can live in an unheated tank at room temperature.”
It is a tropical fish. Below its temperature range it becomes sluggish, stops eating, and is far more prone to disease. A thermostatically-controlled heater is essential.
“The plant-vase "betta gardens" filter the water through the roots.”
They do not provide meaningful filtration, warmth, or swimming space — they are a marketing idea, not a humane home.
When to act
We triage, not diagnose — but these are worth a closer look (starting with a water test):
- Clamped fins, lethargy, or refusing food — check the water first: test temperature, ammonia, nitrite and nitrate before anything else.
- A swollen belly with raised scales (a "pinecone" look) can signal dropsy — a sign of serious internal illness; seek fish-savvy/vet advice.
- Long-term fin loss, white spots, cotton-like growths, or laboured breathing warrant investigation — begin with a water test, then an aquatic vet if it persists.
Sources & further reading
- SeriouslyFish — Betta splendens — Adult size ~70 mm SL; recommended base 45×30 cm (~41 L / 11 US gal), no bowls/jars; temperature 22–30 °C / 72–86 °F; pH 6.0–8.0 (ornamental); hardness 1–15 dGH; gentle sponge filtration; carnivore diet (daphnia/artemia/bloodworm), prone to obesity; solitary, not a community fish; lidded (jumper) + surface-air access.
Written & fact-checked by The Finfern Team against the sources above — kind, general guidance, not a diagnosis. If something looks wrong, test your water and, if it persists, contact a fish-savvy vet.
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