Rectangulus Triggerfish

Rectangulus Triggerfish: The Aggressive Icon

The Rectangulus Triggerfish (Rhinecanthus rectangulus), also known as the Wedge-Tail Triggerfish, Reef Triggerfish, or Humu Humu Triggerfish (the State Fish of Hawaiʻi), is famous for its vibrant, complex pattern and highly territorial behavior.

This species is easily identified by its brown to orange upper body, white belly, and bold black markings, including a distinctive black stripe from the eye to the anal fin and a black, wedge-shaped mark at the base of the tail (caudal peduncle). Growing up to 10-12 inches in length, the Rectangulus Triggerfish requires a minimum aquarium size of 120-180 gallons to accommodate its active swimming and aggressive temperament.

As one of the most aggressive genera (Rhinecanthus), this fish should only be kept in a FOWLR (Fish-Only With Live Rock) system with other large, aggressive tankmates. It is known to rearrange rockwork, and owners must use caution as this fish can inflict a painful bite.

Diet & Compatibility:

• Diet: This trigger is a voracious Carnivore that feeds on nearly all reef invertebrates in the wild, including sea urchins, mollusks, crustaceans, and worms. In the aquarium, it must be fed a varied, high-protein diet of meaty foods like clam, shrimp, squid, and krill.
• Teeth Care: It is essential to regularly provide hard-shelled, meaty foods (such as whole clams or cockles) to prevent its strong, crushing teeth from overgrowing, which can lead to feeding difficulties.
• Reef Compatibility: It is Not Reef Safe. This species will actively hunt and destroy all ornamental invertebrates (shrimp, crabs, snails, clams, urchins, etc.) and is likely to damage corals, making it unsuitable for a typical reef tank.
• Temperament: It is Aggressive and highly territorial. It should be kept singly and is often aggressive towards other triggers. Tankmates should be limited to large, robust, and equally aggressive species. Owners should exercise caution when performing tank maintenance.

Quick Facts

• Scientific Name: Rhinecanthus rectangulus
• Primary Common Name: Rectangulus Triggerfish
• Other Common Names: Wedge-Tail Triggerfish, Reef Triggerfish, Humu Humu Triggerfish
• Origin: Indo-Pacific (including Hawaii)
• Max Size: 10-12 inches (25-30 cm)
• Temperament: Aggressive (One of the most aggressive triggers)
• Diet: Carnivore (Requires hard-shelled food)
• Minimum Tank Size: 120-180+ Gallons
• Reef Compatibility: Not Reef Safe