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No federal permit to keep

Green Plakad

Betta mahachaiensis

Also known as Mahachai Betta, Mahachai Fighter

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

Betta mahachaiensis is a species of bubble-nesting betta native to Thailand, where it occurs naturally near the Gulf of Thailand.

Aquarium hobby
Experience: Beginner
Green Plakad
Photo: panitvong,n, CC BY-SA 4.0, via Wikimedia Commons
FamilyGouramis and bettas
Adult lengthup to 2.4 in
WaterFreshwater, brackish

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 1.7 in / 4.37 cm).
  • Water: Freshwater (tolerates brackish).
  • pH: 6.87–7.8.
  • 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 18 × 12 in (roughly 11 US gallons); space needed is rated “modest tank”.
  • Water: a fairly wide range, from slightly acidic to slightly alkaline, 72–82 °F, pH 7–8.5, 5–20 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 medium-hard to hard fresh or slightly brackish conditions, and does best in a well-planted, shady tank with plenty of surface cover in the form of tall stem or floating plants.”
  • 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

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

This species is part of a group that hobbyists, aviculturists or zoos keep widely (Gouramis and bettas), so it's included for completeness. It may be rare in captivity itself, or not kept at all. Use the group guide as a starting point and look for species-specific advice from experienced keepers.
About this animal

About this animal

It is typically seen in stagnant waters in swamps, pools, and ponds. The species can be found in brackish waters, with salinity levels between 1.1 and 10.6 parts per thousand.

Quoted from the Wikipedia article “Betta mahachaiensis” (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 and brackish water. Uses both the bottom and open water. Encountered in nipa palm (Nypa fruticans) swamps, especially in the water-holding phytotelma of the palm bract, which the pair use for bubble-nest building, courtship, and hatching of fry.
Water it lives inFreshwater / brackish water, pH 6.87–7.8.
ClimateTropical climate.
Behavior to plan forBreeding: clutch tenders, biparental parental care.

What this means for care

  • It tolerates or needs brackish water; check salinity needs before setup.
  • Parents guard eggs or young, so expect territorial behavior when breeding.
  1. FishBase species summary: Betta mahachaiensis
Native climate (measured)

Native climate (measured)

Warm-season highsabout 94°F (up to 94°F in the hottest sampled areas)
Cool-season lowsabout 69°F (down to 69°F in the coldest sampled areas)
Average temperature81–83°F across sampled records
Relative humidity73–74% on average (driest month about 67%)
Rainfallabout 1222 mm a year, with strong wet and dry seasons

Measured at 6 wild occurrence records sampled against WorldClim 2.1 climate data (1970–2000 averages). Air conditions in the range are ecological context, not enclosure settings: microhabitats such as burrows, leaf litter or basking rocks can be cooler, warmer or more humid.

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.

OverviewBetta mahachaiensis is a species of bubble-nesting betta native to Thailand, where it occurs naturally near the Gulf of Thailand. It is typically seen in stagnant waters in swamps, pools, and ponds. The species can be found in brackish waters, with salinity levels between 1.1 and 10.6 parts per thousand. Betta mahachaiensis is capable of living in both fresh water and brackish water, a trait unique among fish in the genus Betta. — 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
BiologyFacultative air-breathing; Encountered in nipa palm ( Nypa fruticans ) swamps, especially in the water-holding phytotelma of the palm bract, which the pair use for bubble-nest building, courtship, and hatching of fry. — 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 sources2in
FishBase 1641.7
Seriously Fish species profiles 1672.4

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.

pH

Average of sources6.9–8.2
FishBase 1646.9–7.8
Seriously Fish species profiles 1677–8.5

Water temperature

Reported72–82°F
Seriously Fish species profiles 16772–82

Range the species tolerates; aim for the middle.

Water hardness

Reported5–20dGH
Seriously Fish species profiles 1675–20

Minimum tank footprint

Reported18in
Seriously Fish species profiles 16718

Seriously Fish recommends a tank base of at least 18 × 12 in (about 11 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.
  9. iNaturalist (captive observations) Community referenceCommunity observation platform run by the California Academy of Sciences and National Geographic; observations marked captive show animals living in homes, zoos and aquariums.