Betta (Siamese Fighting Fish)

Betta splendens is native to the slow, shallow, densely vegetated waters of central Thailand, in and around the Chao Phraya river basin — rice paddies, floodplains, ditches and marshes rather than open river. It belongs to the labyrinth-fish group: it has an accessory breathing organ, the labyrinth organ, that lets it gulp air from the surface, an adaptation to warm, still, low-oxygen water. That ability is often misused to justify keeping bettas in tiny unheated bowls — but the fish still needs clean, warm, stable water to thrive, and the wild form is far plainer than the ornamental strains sold today.

Tank & water. House a single betta in at least 19 litres (5 US gallons), heated to a steady 24–27 °C (75–80 °F), with gentle filtration; bettas dislike strong current and their long fins are easily buffeted by it. They prefer soft to moderately hard water and adapt to a broad pH 6.5–7.5. A lid is essential — they are capable jumpers, and they need access to a warm, humid layer of air above the water for their labyrinth organ; a cold draught on that surface air can chill them.

Temperament. Males are highly territorial and must never be housed together; the trailing-finned show forms are poor swimmers and cannot defend themselves, so they are usually kept as the sole fish or with a few calm, non-nippy tankmates in a larger tank. Fin-nippers such as tiger barbs are a poor match, as are other gouramis, which may provoke aggression.

Diet & care. Bettas are carnivores; feed a betta-specific pellet with occasional frozen or live foods such as daphnia and bloodworm, in small amounts to avoid fouling the water and to prevent bloating. Adult size is about 6–7 cm (2.5 in) and lifespan is typically 3–5 years with good care. Their bright colours and interactivity make them rewarding, but their popularity means welfare shortcuts are common — a heater, a filter and enough water are non-negotiable.