We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Reef Triggerfish?

By R. Britton
Updated May 21, 2024
Our promise to you
AllThingsNature is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At AllThingsNature, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The reef triggerfish, Rhinecanthus rectangulus, or humuhumu-nukunuku-apua'a, is a bottom-feeding marine fish found across a large geographic range. This species can be found around the outer edge of the world's tropical reefs. It is the state fish of Hawaii and has a variety of historical uses in Hawaii, including being the focus of ritual ceremonies. The reef triggerfish is also a popular marine aquarium fish.

This species reaches 1 foot (30 cm) and has a comparatively small mouth at the end of a large, tapering snout. The mouth of the reef triggerfish contains lots of needle-sharp teeth, situated very close together. The fish also has a powerful jaw, making it an efficient marine predator. Primary food sources include algae and other plant matter, crustaceans, sea urchins and mollusks, meaning the reef triggerfish is an omnivore. The wide, varied diet of this fish also incorporates small fish and marine invertebrates.

The reef triggerfish is rather unusual because it has the ability to move each eye in a different direction at the same time. One theory surmises that this allows the fish to search the sea floor for prey while simultaneously scanning for potential threats. Able to swim forwards and backward by undulating its dorsal and anal fins, the reef triggerfish is reasonably agile, able to out-maneuver both prey and predators. If threatened, the fish makes a deep grunting noise as it swims for safety.

Two spines are situated on top of the body just behind the head. The larger of the two spines can be raised and slopes backward. The smaller of the two spines slopes forward when raised, slotting under the larger spine. This creates a strong wedge-shape that the reef triggerfish uses to wedge tight into small gaps and crevices. Once wedged into place, this makes the fish incredibly difficult for predators to extract.

Although a popular marine aquarium species, the reef triggerfish can be very aggressive and territorial, so it is not advisable to keep more than one reef triggerfish per tank. In captivity, the fish should have plenty of places to hide and lots of open space in which to swim freely. The reef triggerfish will eat any other fish small enough to fit in its mouth and will also devour any marine invertebrates in the tank. The reef triggerfish is reasonably easy to keep in an aquarium setting — providing the tank is large enough and not too overcrowded — because they are hardy, not prone to disease and can tolerate changes in water condition.

Frequently Asked Questions

What is a reef triggerfish and where can it be found?

The reef triggerfish, also known as the rectangular triggerfish or by its Hawaiian name 'humuhumunukunukuapua'a', is a tropical marine fish native to the Indo-Pacific region. It's commonly found in coral reefs where it feeds on algae, crustaceans, and small invertebrates. This species is particularly abundant around the Hawaiian Islands, where it's recognized as the state fish.

How does the reef triggerfish get its name?

The name "triggerfish" comes from its unique dorsal spines. The first spine, or 'trigger', can be locked upright and is used to wedge the fish securely into crevices, deterring predators. The second spine, which is smaller, 'triggers' the locking and unlocking of the first spine, hence the name 'triggerfish'.

What are the distinctive features of a reef triggerfish?

A reef triggerfish boasts a diamond-shaped, laterally compressed body with bold, geometric patterns. Its coloration is a mix of tan, yellow, and black, which provides camouflage among the coral. It has small, but strong jaws with teeth adapted for crushing shells, and its anterior dorsal fin is modified into the characteristic trigger spine.

What is the ecological role of the reef triggerfish in its habitat?

As a benthic feeder, the reef triggerfish plays a crucial role in controlling the population of bottom-dwelling invertebrates and algae in coral reef ecosystems. By consuming these organisms, it helps maintain the balance and health of the reef, which in turn supports biodiversity and provides a habitat for numerous marine species.

How does the reef triggerfish behave when threatened?

When threatened, the reef triggerfish uses its unique dorsal spine mechanism to lock itself into rock crevices, making it difficult for predators to extract it. Additionally, it can produce a grunting sound that may startle predators or communicate distress to other triggerfish, showcasing a fascinating aspect of its behavioral defense strategies.

Is the reef triggerfish important to local cultures or economies?

Yes, the reef triggerfish holds cultural significance, especially in Hawaii where it's the official state fish and a symbol of the local natural heritage. It's also a popular species in the aquarium trade due to its striking appearance and interesting behavior, contributing to local economies through sustainable fishing practices and ecotourism activities.

AllThingsNature is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

AllThingsNature, in your inbox

Our latest articles, guides, and more, delivered daily.

AllThingsNature, in your inbox

Our latest articles, guides, and more, delivered daily.