Stripe-nosed Halfbeak (Zenarchopterus buffonis)

Stripe-nosed Halfbeak (Zenarchopterus buffonis)

A small school of Stripe-nosed Halfbeaks found in Pasir Ris Park's Mangrove Boardwalk during high tide. (Photograph by: Lumin Ong)

Family: Zenarchopteridae
Species Name: Zenarchopterus buffonis
Common Name(s): Stripe-nosed Halfbeak, Buffon's River-garfish

Presence in Singapore: Native
Habitat: Estuaries, also occurs in full saltwater along the coast
Conservation status: Least Concern (Red Data Book 3)

A common and usual sight in our estuaries and other coastal habitats, this surface-dwelling fish is usually sighted in schools of varying numbers. It is also known to travel up tidal rivers. Although capable of reaching 23cm in length, this fish is usually seen half that size. As a halfbeak, its lower jaw is much longer than its upper jaw, which aids in feeding at the surface as it forages for fallen insects and other organic matter. Being in the family Zenarchopteridae (Viviparous Halfbeaks), this species is ovoviviparous where the eggs are fertilized and hatch internally.

It is very similar-looking to the lesser-known Shortnose River Garfish (Zenarchopterus gilli).  In general, the Stripe-nosed Halfbeak has a bold stripe that stretches at least past the head, which is missing or very faded in the Shortnose River Garfish. The lower jaw of the Stripe-nosed Halfbeak is also thinner and longer compared to the Shortnose River Garfish. The tip of both species' lower jar is shiny and bright.

To be more accurate, one must look at the male's andropodium (a modified anal fin used to deliver sperm to the females):

Stripe-nosed Halfbeak - small andropodium barely or not reaching the base of the tail.
Shortnose River Garfish - enlarged andropodium reaching the tip of the tail.

The juvenile Stripe-nosed Halfbeak has two solid white bands as seen below.

References

• FishBase. Zenarchopterus gilli Smith, 1945 – Viviparous Halfbeak. Retrieved from https://fishbase.mnhn.fr/summary/Zenarchopterus-gilli.html.
• FishBase. Zenarchopterus gilli Smith, 1945 – Viviparous Halfbeak. Retrieved from https://fishbase.mnhn.fr/summary/Zenarchopterus-gilli.html.
• Lim, K.K.P. & Low, J.K.Y. 1998. A Guide to Common Marine Fishes of Singapore. Singapore Science Centre, 163 pp. ISBN 981-00-9904-5.
• National Parks Board (NParks). Marine Fishes. Retrieved from https://www.nparks.gov.sg/nature/species-list/marine-fishes.