All fish / Zenarchopteridae

Wrestling Halfbeak

Dermogenys pusilla

Also known as halfbeak, malayan halfbeak, wrestling half beak, pygmy halfbeak, silver halfbeak, dermogenys, ปลาเข็ม, ikan julung-julung, ハーフビーク, 鱵鱼, 皮颏鱵

A slim, silvery fish with a long, fixed lower jaw, and males often show red or yellow marks on the fins. It spends its time right at the surface hunting insects, and people keep it for its unusual look and the way males spar by locking jaws.

Care at a glance

Care level

Moderate

Temperament

Semi

Adult size

6 cm

Temperature

22 to 28 °C

pH

6.5 to 8

Smallest tank

60 litres

Keep as

One male with several females, or a larger group with plenty of surface cover

Diet

Carnivore: small floating insects such as fruit flies and mosquito larvae, plus brine shrimp, daphnia and floating flake

Swims

Top of the tank

Lifespan

2 to 4 years

Water

Freshwater

Wild range

Southeast Asia: Thailand, Malaysia, Singapore, Indonesia (Sumatra, Java, Borneo)

Breeding

Livebearer with internal fertilisation; females give birth to about 10 to 30 fully formed fry after roughly four weeks. Breeding happens readily, but stillbirths are common if the diet is poor, and the fry need tiny live food and should be moved away from the adults.

Good to know

They jump and panic easily, so a tight lid is needed and they can damage their delicate beaks on the glass. Males fight each other, and the fish do best with a little salt or hard water, though they are not true brackish fish.