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No federal permit to keepSumatra Betta
Betta falx
Fishes › Gouramis, bettas, snakeheads (Anabantiformes) › Osphronemidae (Gouramis and bettas)
Betta falx is a species of betta endemic to the island of Sumatra in Indonesia.
Care at a glance
Species-specific aquarium care
- Tank: At least 24 in long and 12 in front to back for one adult (adults commonly reach about 1.4 in / 3.49 cm).
- Water: Freshwater.
- Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.
- Availability: Rarely or never seen in the aquarium trade; expect to source it from specialists or not at all.
Calculated from this species' own FishBase record: tank size from its typical adult length and swimming zone, water values from its recorded ranges. The group guide below fills in general care.
Care guide
Species care notes
- Tank: a base of at least 24 × 12 in (roughly 14 US gallons); space needed is rated “modest tank”.
- Water: soft, acidic water, 72–81 °F, pH 4.7–6.8, 0–5 dGH.
- Behaviour: temperament species tank; in a pair; not a community fish.
- Difficulty: Moderate (Seriously Fish rating).
Short excerpts from the species profile:
- Setup: “Can be maintained in a fully-decorated aquarium although many breeders prefer not to use a substrate for ease of maintenance.”
- Diet: “Likely to prey on insects and other small invertebrates/zooplankton in nature.”
- Tankmates: “Not recommended for the standard community set-up for reasons already touched upon.”
From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167
Bettas (fighting fish)
Applies to most species in this group. Habitat: Shallow rice paddies and marshes. Individual species can differ, so compare with the species numbers above and the linked sources.
Housing & setup
- A heated, filtered tank of at least 5 gallons, with gentle flow and plants.
- Domestic B. splendens should generally be maintained alone. Other Betta species need their own compatibility plan; B. imbellis can be maintained as a pair with adequate cover.
Diet
- Betta pellets plus frozen foods.
Social life
- Use species-specific social housing: B. splendens alone under the detailed Seriously Fish recommendation; B. imbellis may be housed as a compatible pair.
Health watch
- Fin rot in dirty water; never keep bettas in tiny unheated bowls.
Understanding the animal
About this animal
About this animal
It is an inhabitant of acidic, nearly stagnant water, where it can be found amongst the vegetation along the banks. This species grows to a length of 3.5 cm (1.4 in).
Quoted from the Wikipedia article “Betta falx” (CC BY-SA 4.0) 174
In the wild
In the wild
From this species’ own FishBase record (habitat, bottom type, water and breeding data), not its family. Good care copies these conditions.1
| Where it lives | Lives in freshwater, in mangroves. Uses both the bottom and open water. Typically found among submerged bank vegetation, in near stagnant waters, with pH 4.7-6.8. Latin word falx means scythe, alluding to the continuous curved shape of the broad anal and caudal distal margins of a male in display. Caudal fin rounded. |
| Water it lives in | Freshwater. |
| Climate | Tropical climate. |
From the sources
From the sources
Quoted from the matching sections of reputable sources for this exact species. Specialist databases are used first; Wikipedia (community-edited, CC BY-SA 4.0) only fills gaps. Other sources are short credited quotes.
| Where it lives | Home ranges Population dynamics Growth parameters Max. ages / sizes Length-weight rel. Length-frequencies Mass conversion Recruitment Abundance Life cycle Reproduction Maturity Maturity/Gills rel. — FishBase |
| Biology | Facultative air-breathing; Typically found among submerged bank vegetation, in near stagnant waters, with pH 4.7-6.8. Latin word falx means scythe, alluding to the continuous curved shape of the broad anal and caudal distal margins of a male in display. — FishBase |
Data and studies
The numbers
The numbers
Each bar is what one source reports. Where several sources weigh in, the dashed gold band marks their average.
Adult length
Maximum recorded length. Measured as standard length (snout to the base of the tail, not counting the tail fin). Fish in home aquariums often stay smaller than wild records.
Water temperature
Range the species tolerates; aim for the middle.
pH
Water hardness
Minimum tank footprint
Seriously Fish recommends a tank base of at least 24 × 12 in (about 14 US gallons).
Sources for this sheet
- FishBase (Froese & Pauly, eds.), version 24.07 Peer-reviewed researchThe global scientific database on fishes, maintained by a consortium of research institutions; every value is referenced.
- Seriously Fish species profiles Experienced keeper or breederLong-running aquarium reference written and peer-checked by experienced fishkeepers and ichthyologists; each profile covers habitat, tank size, water, diet, behaviour and breeding.
- Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Types and features of aquatic systems Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
- Seriously Fish — Betta splendens Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Seriously Fish — Betta imbellis Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
- Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.
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