Rex halfbeak

Nomorhamphus rex

Also known as Celebes halfbeak rex

FreshwaterFish

Rex halfbeak (Nomorhamphus rex) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 72–79°F (22–26°C)
pH: 6.8–7.8
Adult size: 2.2 in (5.5 cm)
Minimum tank: 20 gal (75 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Top
Difficulty: Medium
Breeding: Medium
Rarity: Rare
Origin: Southern Sulawesi streams
Family: Zenarchopteridae

Overview

A stream halfbeak that patrols the surface, taking small prey with its beaked jaws. Keep it as a small group with more females than males, since rival males display and squabble at the top of the tank and a harem spreads that pressure out. It is peaceful toward other fish and suits calm mid and lower tankmates that leave the surface to it, avoiding anything large, nippy or boisterous. Feed floating and surface foods: small live and frozen insects, mosquito larvae, daphnia and fine floating dried foods; it will mostly ignore food that sinks. It likes cooler, flowing, harder water, so give it a planted, well-covered tank of around 75 liters with gentle current.

In the wild

The rex halfbeak comes from clear hill streams of southern Sulawesi, flowing water that runs cooler and harder than a typical blackwater tank. Keep it on the cool side, about 22 to 26 C, in neutral to slightly alkaline water around pH 6.8 to 7.8, with moderate flow and good oxygen. A planted tank with an open surface, some current and a firm lid suits it, since like all halfbeaks it will jump.

Good to know

Nomorhamphus rex is a halfbeak of the family Zenarchopteridae, described in 2012 and endemic to southern Sulawesi. It reaches about 5.5 centimeters, females a little larger than males, with yellow ventral fins, a red lower beak and black-edged fins. It is a livebearer: the male fertilises the female internally with a modified anal fin, and she gives birth to live young, a spawning of moderate difficulty.

Did you know

The name rex, meaning king, was not chosen for its bearing. The describers gave it that name because the fish's teeth reminded them of the teeth of Tyrannosaurus rex.