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Krabi mouth-brooding betta

Betta simplex

Also known as Krabi mouth brooder betta, Krabi Mouth Brooding Betta

Fishes › Gouramis, bettas, snakeheads (Anabantiformes) › Osphronemidae (Gouramis and bettas)

The Krabi mouth-brooding betta (Betta simplex) is a species of gourami endemic to Krabi Province, Thailand.

Aquarium hobby
Experience: Beginner
Krabi mouth-brooding betta
Photo: Andrewbogott, CC BY-SA 3.0, via Wikimedia Commons
FamilyGouramis and bettas
Adult lengthup to 3.1 in
WaterFreshwater

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 3.1 in / 8 cm).
  • Water: Freshwater.
  • Temperature: 72–79°F (range recorded for this species).
  • Layout: Uses both the bottom and open water: give open swimming space plus cover near the substrate.

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: a fairly wide range, from slightly acidic to slightly alkaline, 68–82 °F, pH 7–8, 3–12 dGH.
  • Behaviour: temperament species tank; in a pair; not a community fish.
  • Difficulty: Moderate (Seriously Fish rating).

Short excerpts from the species profile:

  • Setup: “This species does best in a well-planted, shady aquarium with plenty of surface cover in the form of tall stem plants, floating types such as Salvinia or Riccia spp., or tropical lilies from the genus Nymphaea.”
  • Diet: “Likely to prey on aquatic and terrestrial invertebrates in nature.”
  • Tankmates: “Not recommended for the standard community aquarium.”

From the Seriously Fish profile for this species, which has the full habitat, maintenance, diet, behaviour and breeding write-up 167

Group care guide

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.

Sources 117119164118252253

Diet

  • Betta pellets plus frozen foods.

Sources 117119164118252253

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.

Sources 117119164118252253

Health watch

  • Fin rot in dirty water; never keep bettas in tiny unheated bowls.

Sources 117119164118252253

Understanding the animal

About this animal

About this animal

It inhabits karst springs and wetlands, where it lives amongst vegetation close to the banks. This species can reach a length of 8 cm (3 in).

Quoted from the Wikipedia article “Krabi mouth-brooding betta” (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 livesLives in freshwater. Uses both the bottom and open water. Inhabits limestone streams and marshes.
Water it lives inFreshwater, 72–79 °F (22–26 °C), pH 7, hardness 11 dH.
ClimateTropical climate.

What this means for care

  • Keep water within its wild range, 72–79 °F.
  1. FishBase species summary: Betta simplex
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.

OverviewThe Krabi mouth-brooding betta (Betta simplex) is a species of gourami endemic to Krabi Province, Thailand. It inhabits karst springs and wetlands, where it lives amongst vegetation close to the banks. This species can reach a length of 8 cm. This species can also be found in the aquarium trade and is taken from the wild for this purpose. — Wikipedia (community-edited)
Where it livesHome 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
Appearance and sizeThe Krabi mouth-brooding betta is an oblong fish with rounded fins, growing to a length of about 8 cm. The basic colour is yellowish-brown or greyish-brown with three faint longitudinal stripes. The gill-cover has a bluish-green patch and the fins have a blue iridescence. — Wikipedia (community-edited)
BiologyFacultative air-breathing; Inhabits limestone streams and marshes. The type locality was described as a pool of 10-15 m diameter, up to 10 m deep and the species was collected along the banks. Water data reported was 27 °C, pH 7.0, electric conductivity 530 µS/cm. — 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

Average of sources2.8in
FishBase 1643.1
Seriously Fish species profiles 1672.4

Maximum recorded length. Measured as total length. Fish in home aquariums often stay smaller than wild records.

Water temperature

Average of sources70–80.5°F
FishBase 16472–79
Seriously Fish species profiles 16768–82

Range the species tolerates in nature; aim for the middle.

pH

Reported7–8
Seriously Fish species profiles 1677–8

Water hardness

Reported3–12dGH
Seriously Fish species profiles 1673–12

Minimum tank footprint

Reported24in
Seriously Fish species profiles 16724

Seriously Fish recommends a tank base of at least 24 × 12 in (about 14 US gallons).

Sources for this sheet

  1. 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.
  2. 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.
  3. Merck Veterinary Manual: Management of aquarium fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
  4. 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.
  5. Merck Veterinary Manual: Nutritional diseases of fish Zoo, university or veterinaryThe Merck Veterinary Manual: a standard veterinary reference written and reviewed by veterinary specialists.
  6. Seriously Fish — Betta splendens Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
  7. Seriously Fish — Betta imbellis Zoo, university or veterinaryAdded in the 2026 source-checked care-guide review.
  8. Wikipedia (species article) Community referenceFree encyclopedia; useful overviews with their own citations. Intro text is quoted under CC BY-SA 4.0.