Hawaii Reef Fish Identification Guide: 25+ Species

Hawaii's reef fish are among the most distinctive in the Pacific, with a high rate of species found nowhere else on Earth. About 25% of Hawaii's 685 marine fish species are endemic, the result of the islands' extreme geographic isolation. When you snorkel at Hanauma Bay, Molokini Crater, or any other Hawaiian reef, you are looking at a community of animals that evolved over millions of years in relative isolation. This guide identifies the most commonly encountered species so you can recognize them in the water.

Hawaii reef fish: an introduction

Hawaiian reef fish live in the shallow coastal waters from the surface to about 180 feet, in and around the coral reef systems that ring the islands. The reefs here are composed primarily of stony corals, and the fish communities that inhabit them have evolved in close relationship with the coral structure. Understanding a few basic behaviors, how parrotfish feed, how cleaner wrasses operate, how surgeonfish school, makes the reef more legible and the snorkeling more engaging.

None of the commonly encountered reef fish in Hawaii are dangerous to snorkelers who behave normally. The rules are simple: do not touch, do not chase, do not corner, do not block a fish's path, and do not try to feed fish. Feeding disrupts natural behavior and the delicate balance of the reef ecosystem. Observe and appreciate; leave everything in place.

Humuhumunukunukuapua'a (Hawaii State Fish)

Scientific name: Rhinecanthus rectangulus
Common name: Rectangular triggerfish, reef triggerfish
Length: Up to 10 inches

The humuhumunukunukuapua'a (hoo-moo-hoo-moo-noo-koo-noo-koo-ah-poo-ah-ah) is the official state fish of Hawaii and the most phonetically challenging name in the islands. The name translates approximately as "fish that grunts like a pig," which is accurate: when threatened, the fish makes a grunting sound and backs into a coral crevice, locking itself in place with a spine on its dorsal fin.

What it looks like: An angular, roughly rectangular body with a distinctive color pattern: yellow-brown back, white and blue lower body, and a large black patch behind the head with two horizontal blue stripes. The face has fine blue lines radiating from around the mouth and a yellow-orange stripe running from the jaw to the pectoral fin. Unmistakable once seen.

Where to see it: Common throughout Hawaiian reefs from 1 to 60 feet. Highly active during the day; shelters in crevices at night. Regularly seen at Hanauma Bay, Molokini, and most other snorkel sites. Usually solitary or in pairs.

Behavior: Territorial and curious. Will approach snorkelers briefly before retreating. Feeds on algae, sea urchins, and invertebrates by blowing jets of water at the bottom to dislodge prey.

Tangs and surgeonfish

Surgeonfish get their name from the sharp, scalpel-like spine on either side of the base of the tail, used for defense. They are among the most abundant reef fish in Hawaii.

Yellow tang (Zebrasoma flavescens): A vivid, solid yellow oval disc with a white spine at the tail base. One of the most commercially collected reef fish in the world for aquariums; Hawaii provides a significant fraction of the global supply. Schools of yellow tang move through reefs, grazing on algae. Endemic to Hawaii. Common at most snorkel sites from 10-150 feet.

Convict tang (Manini / Acanthurus triostegus): White body with six bold vertical black stripes (hence "convict"). Schools of dozens to hundreds are routine in shallow reef areas, particularly at Hanauma Bay. The Hawaiian name manini has entered Hawaii Pidgin as slang meaning stingy, cheap, or insufficient. Common from 1-15 feet.

Achilles tang (Acanthurus achilles): Deep black body with a brilliant orange-red teardrop patch at the tail and orange accents on the fins. One of the most striking fish in Hawaii. Endemic to the Indo-Pacific but strongly associated with Hawaiian wave-swept reef areas. Not as common as yellow or convict tangs but reliably seen at shallower, more exposed reef sections.

Palette surgeonfish (Dory / Paracanthurus hepatus): Bright blue body with a black palette design and a yellow tail. Widely recognizable from the film "Finding Nemo." Common in Hawaii in both shallow and deep water. Usually seen in pairs or small groups near coral.

Orangeband surgeonfish (Acanthurus olivaceus): Pale olive-gray body with an orange band running from behind the eye. Large adults can exceed 12 inches. Common in Hawaii; frequently seen grazing on sandy bottoms near reef edges.

Parrotfish

Parrotfish are among the most ecologically important fish on Hawaiian reefs. Their fused beak-like teeth scrape algae from coral rock and dead coral, and the ingested coral is ground up in the digestive tract and excreted as fine white sand. A significant portion of the white sand on Hawaiian beaches was produced by parrotfish. The scraping sound of parrotfish feeding is clearly audible underwater.

Bullethead parrotfish (Chlorurus sordidus): The most common parrotfish in Hawaii. Females and juveniles are brown and red; males are vivid green and blue. This color difference (females being dull, males being bright) is typical of parrotfish and causes them to be frequently misidentified as different species. Large males can reach 14 inches.

Spectacled parrotfish (Chlorurus perspicillatus): Large (up to 24 inches), with terminal-phase males showing brilliant blue-green coloring. One of the larger parrotfish species in Hawaii. Often seen alone, feeding actively on the reef.

Redlip parrotfish (Scarus rubroviolaceus): Terminal-phase males are turquoise-blue with red lips and a distinctive hump on the forehead. One of the largest parrotfish in Hawaii, reaching up to 26 inches. Found in deeper water than most parrotfish, typically 15-60 feet.

Palenose parrotfish (Scarus psittacus): Dull-colored initial phase (brown-orange); terminal males are green-blue with a pale zone behind the mouth. Small (8-12 inches) and common on shallow reefs.

Wrasses

Wrasses are one of the most species-rich families in Hawaiian waters. They are active, fast-moving fish that are often observed in mid-water or darting across the reef.

Saddle wrasse (Thalassoma duperrey): The most abundant fish on Hawaii's shallow reefs. Males have a green body, orange head, and a distinctive white saddle marking behind the head. Females are duller green-orange. Extremely common at all snorkel sites. Endemic to Hawaii.

Christmas wrasse (Thalassoma trilobatum): Vivid red-green pattern in males; females are dark reddish. Named for its holiday colors. Active and curious; often approaches snorkelers. Common from 1-40 feet.

Hawaiian cleaner wrasse (Labroides phthirophagus): Small (4 inches), with a brilliant purple body fading to blue and yellow. Operates cleaning stations on the reef where other fish queue to have parasites and dead tissue removed. The cleaner wrasse is the fish equivalent of a dental hygienist. Endemic to Hawaii. A cleaning station in action is one of the most fascinating things to observe on any Hawaiian reef.

Dragon wrasse (Novaculichthys taeniourus): Juveniles look like drifting pieces of algae, mottled green-white with elaborate fin extensions. Adults are darker and more streamlined. The transformation between juvenile and adult is one of the most dramatic in any Hawaiian reef fish.

Rockmover wrasse (Novaculichthys taeniourus): Small, elongated; uses its snout to flip and move rubble and small rocks while hunting for prey underneath. Can be seen actively working the sandy bottom near reef edges.

Butterflyfish

Butterflyfish are among the most visually distinctive reef fish, typically flat-bodied, brightly colored, and often seen in mated pairs. Many species feed on coral polyps, so their presence indicates a healthy reef.

Ornate butterflyfish (Chaetodon ornatissimus): Striking orange stripes on a white body with a black stripe through the eye. Usually seen in pairs. Common throughout Hawaiian reefs from 5-50 feet.

Lined butterflyfish (Chaetodon lineolatus): Largest butterflyfish in the Pacific. White body with many thin black vertical lines, a black eye mask, and a black rear body band. Usually in pairs. Feeds on coral polyps and sea anemones.

Threadfin butterflyfish (Chaetodon auriga): White with diagonal lines crossing both halves of the body, a black eye stripe, and an orange rear patch. One of the more commonly seen butterflyfish in shallow Hawaiian waters.

Milletseed butterflyfish (Chaetodon miliaris): Yellow body with rows of small dark spots (the milletseed pattern). Endemic to Hawaii. Common and often abundant in large schools. One of the few butterflyfish that schools rather than pairing.

Raccoon butterflyfish (Chaetodon lunula): Brown-yellow with a distinctive raccoon-like black and white face mask and a white saddle behind the head. Nocturnal and secretive; more commonly seen after dark, though present on the reef during the day in shaded areas.

Angelfish

Potter's angelfish (Centropyge potteri): Orange body with blue-black scale edging and blue-black posterior. Endemic to Hawaii and one of the most distinctive small fish on the reef. Shy and difficult to photograph; retreats into crevices when approached. Usually seen flitting along coral at 10-60 feet.

Bandit angelfish (Apolemichthys arcuatus): White body with a bold black diagonal band from the dorsal fin to the pectoral fin. Unusual in its coloration compared to most angelfish. Found in deeper water (60-300 feet), occasionally seen by snorkelers at the upper range.

Other notable species

Moorish idol (Zanclus cornutus): Not a butterflyfish despite the resemblance. Highly distinctive: vertical black and white stripes, an elongated dorsal fin streamer, and a yellow saddle. Usually in pairs, near coral from 5-180 feet. One of Hawaii's most-photographed reef fish.

Trumpetfish (Aulostomus chinensis): Extremely elongated (up to 3 feet), hanging vertically in the water column or drifting horizontally alongside large fish to ambush prey. Can change color between tan, brown, and pale yellow. Patience will reveal one near most Hawaiian reefs.

Spotted pufferfish (Arothron meleagris): Round, gray-white with black spots and yellow-orange accents, inflates when threatened. Moves slowly and deliberately. Do not approach closely. Common in Hawaiian reefs from 3-80 feet.

Hawaiian lionfish / Turkeyfish (Pterois sphex): Striped red and white with long, venomous fin spines. Endemic to Hawaii. Secretive; hides under ledges and in crevices during the day. Do not touch the fin spines.

Snowflake moray eel (Echidna nebulosa): White with black spots and yellow highlights. Hides in reef crevices with its head visible. Not aggressive unless a hand is put into a crevice. Do not insert fingers into any crack in the reef.

Needlefish (Belonidae): Long, slender, silver fish that cruise in groups just below the surface. Harmless but startling when encountered suddenly at the surface.

Whitetip reef shark (Triaenodon obesus): Slim, gray, with white-tipped dorsal and tail fins. Rests on the bottom in deeper areas of reefs and caves. Not aggressive toward snorkelers. Common at sites like Molokini back wall and deeper sections of outer bay reefs. Maintain calm and distance.

Sea turtles and marine mammals

Green sea turtle (Honu / Chelonia mydas): The most commonly encountered large marine animal at Hawaiian snorkel sites. Adults are large, up to 3 feet across the shell, with a smooth, streamlined profile. They rest on sandy bottoms, graze on algae on the reef, and surface regularly to breathe. Federal protection applies: maintain a 10-foot distance, never touch, never block their path to the surface, and do not position yourself between a turtle and open water.

Hawaiian monk seal (Neomonachus schauinslandi): One of the most endangered marine mammals in the world, with a population of around 1,500. Occasionally hauls out on beaches or rests in the shallows. Endangered Species Act protection: stay 50 feet away. Do not approach, do not attempt to interact. If a seal is on the beach, give it a wide berth and keep children and dogs well away.

Spinner dolphin (Stenella longirostris): Resident pods inhabit coastal waters, resting in calm bays in the morning. Federal regulations require snorkelers and swimmers to stay 50 yards away. Do not enter the water with spinner dolphins intentionally, and if they approach while you are snorkeling, maintain position and do not pursue them. Night-feeding spinner dolphins require rest during the day; disturbing their rest cycles is a genuine threat to their health.

Tips for identifying fish underwater

Focus on shape first, then color. Color varies significantly between males, females, juveniles, and adults of the same species. Body shape (round, elongated, triangular, disk-like) is a more reliable initial identifier.

Note the key marks. Most reef fish have one or two distinctive markings: an eye stripe, a spot near the tail, a distinctive fin, or a color band. Those distinctive marks are what field guides key on.

Buy or borrow a waterproof ID card. Small laminated reef fish identification cards (available at dive shops and online) are extremely useful for immediate identification while snorkeling. The Hawaiian reef fish ID cards by Charles Pukui or the Reef Fish Hawaii cards from the Bishop Museum Press are the standard references.

Use iNaturalist after the visit. Photograph or sketch what you saw and enter it in iNaturalist, a global biodiversity network with active Hawaii contributors. The community identification is remarkably accurate and builds your knowledge over time.

For the best places to see these species in person, see the Hawaii snorkeling guide, the Maui snorkeling guide, and the Hanauma Bay guide.