Furry Diary

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Wrestling Halfbeak

Dermogenys pusilla

Also called Malayan halfbeak, Silver halfbeak, Golden halfbeak

SpeciesShort profile

From Fresh and brackish waters of South-east Asia, described from Bogor, Java; reported from Thailand, Malaysia, Singapore, Sumatra and Borneo, with wider ranges given in some sources.123

At a glance the quick version

Length5.5 to 7 cm13
Sizesmall
Fascinating jaw-wrestling displays
Lively surface swimmer
Adaptable to fresh or slightly brackish water
13

Looks how to spot one

Slender halfbeak

A thin, pencil-shaped surface fish with a long, fixed lower jaw. Males are smaller than females and have a modified anal fin used in mating.31

ColoursSilvery to golden bodyRed or yellow patches on dorsal fin and beak (males)13

Personality what they are like

Timid at first but lively once settled. Males spar by locking jaws, though in aquaria the weaker fish usually backs off quickly without harm.13

Daily activity how busy a day looks

Active at the surface; an excellent jumper that needs a tight lid.3

Grooming and care the hands-on bits

Changes in pH and hardness should be made slowly. Floating plants give cover and help it feel secure.13

Home where they are happiest

Aquarium from about 60 x 38 x 30 cm (around 68 litres) for a small group, with a tight lid and floating plants. Water 24-28 °C, pH 6.5-8.0, 10-20 dGH. Copes with soft water through to slightly brackish.321

Food basics what goes in the bowl

Surface feeder: small insects such as fruit flies, mosquito larvae, brine shrimp and bloodworm; often learns to take dry food over time.312

Company who they like around

Calmer in groups. Keep either one male or several, with peaceful, similar-sized tankmates such as livebearers, rainbowfish or gobies.3

The story where it all began

Heinrich Kuhl and Johan Coenraad van Hasselt described the species in 1823 from Bogor on Java. Its common name comes from the males' habit of wrestling with locked jaws.1

Fun facts for the dinner table

  1. 1

    Males settle disputes by locking jaws in contests that can last up to 30 minutes.1

  2. 2

    Females give birth to about 20 young after roughly a month.1

  3. 3

    It is a strong jumper, so a lid is essential.3

  4. 4

    It snaps up insects that fall onto the water surface.1

Recognised by the official bits

IUCN Red List
Data Deficient (assessed 2020)2
Taxonomy
Family Zenarchopteridae; described by Kuhl and van Hasselt in 18231

The care rhythm Furry Diary remembers it for you

A typical home-care rhythm for a Wrestling Halfbeak. It is our own starting plan, not a vet's advice, and you can change every line in the app.

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Where this comes from

Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at [email protected] and we will fix it.

  1. Wikipedia: Dermogenys pusilla en.wikipedia.orgused for names, range, behaviour, history
  2. FishBase: Dermogenys pusilla fishbase.seused for environment, diet, IUCN
  3. Seriously Fish: Dermogenys pusilla seriouslyfish.comused for tank size, water, diet, behaviour

Checked 2026-09-30. Text is written in our own words from these sources.