Family: Osphronemidae
A semi-aggressive carnivore osphronemidae from Southeast Asia (Thailand and the Malay Peninsula) — beginner-friendly.
A Osphronemidae species: Betta imbellis lives upper; surface-oriented over clear streams, rivers and still waters. Semi-aggressive; one male per tank. Adults reach 4.2–6 cm. It is one of the aquarium-kept Betta species we profile, alongside Betta smaragdina, Betta splendens, Betta albimarginata.
B. imbellis is the wild-type crescent betta — smaller (6 cm), metallic green with red edging, and comparatively mellow. B. splendens is the domesticated form with huge showy fins and far more aggression. Note 'peaceful' is relative: two males will still fight.
One male with one female, or a single fish, is safest. Two males may coexist in 60 L or more with dense plant barriers, but a deadly fight can erupt anytime. For a group, try 1 male and 2 females and keep a spare tank ready.
Its jump rating is high — wild fish come from shallow swamps and launch explosively when startled or hunting. A lid with no gaps is mandatory; it's among the most frequent jumpers reported by Chinese hobbyists. It also jumps during water changes.
Yes. The ideal band is 24–28 °C; below 22 °C it loses appetite and catches ich more easily. It tolerates cool water slightly better than splendens, but chronic chill still shortens its life. A 25–50 W heater with a guard in a small tank is right.
Carnivores — in the wild, insects and fallen invertebrates. Betta pellets, bloodworms, brine shrimp and mosquito larvae all work well. They feed at the surface, so fast-sinking food just gets wasted.
Bubble-nesting is breeding instinct and a good sign — a nest means water and temperature are right. Ignore a single male's nest; to breed, introduce a ripe female to the nesting male, and he'll catch the eggs under the nest.
Moderate aeration helps. Like splendens it has a labyrinth organ and won't drown quickly, but above 28 °C or at high density it slowly suffocates. A sponge filter in a small tank is perfect — aeration, filtration and gentle flow in one.
Soft and slightly acidic: pH 6.0–7.0, GH 5–12. Neutral tap water adapts fine, but for peak color add Indian almond leaves to mimic the blackwater home. Stability matters more than hitting exact numbers.
Far more tolerant than splendens: small tetras, corydoras and shrimp are mostly safe (it will eat shrimplets). Avoid long-finned showy fish that trigger aggression, and nippy fish that shred its fins.
A step harder than splendens but very doable. After the male nests, add a ripe female; remove her right after spawning (he attacks her) and let the male tend the eggs — about 2 days to hatch, guarding until the fry swim free. Fry take microworms or fine baby brine shrimp.