Nohu ʻOmakaha: Hawaiʻi’s Devil Scorpionfish
Pronunciation: Nohu ʻomakaha, approximately “noh-hoo oh-mah-kah-hah,” with a brief catch before “oh.”
Meet the Devil Scorpionfish
Some fish announce themselves with bright stripes. The devil scorpionfish (Scorpaenopsis diabolus) takes the opposite approach: it sits so still and blends in so well that you might mistake it for part of the reef. Known in Hawaiian as nohu ʻomakaha, it is an ambush predator with a patient hunting style and a very fast finish. [1, 2]
Its quiet appearance hides two surprises: a mouth that can engulf a passing meal in a fraction of a second, and colorful pectoral fins normally concealed against its body. [2]
A Fish Disguised as Reef
Devil scorpionfish spend much of their time motionless on the seafloor. Their camouflage helps them avoid being noticed by prey and predators alike. Fleshy flaps and small tentacle-like structures, found among these scorpionfishes, add to the irregular appearance that makes them difficult to pick out against the reef. [1, 2]
That camouflage is not just a hiding place. It is part of the hunting strategy. Instead of constantly swimming after food, the fish waits for a smaller animal to venture within reach. [2]
What to Look For
Finding a camouflaged fish often means looking for a recognizable feature within what otherwise seems to be background. With a devil scorpionfish, an eye, the outline of the head, or the edge of a fin may reveal that a supposed piece of reef is alive.
Its most vivid colors are usually hidden. The undersides of the pectoral fins carry bold orange, yellow, and black markings. When the fish rests, those fins stay close to the body; when threatened, it can spread them to reveal the warning display. [2]
There is no need to provoke the fish to see those colors. A warning display is a sign to give it space, not a photo opportunity to create.
How Does an Ambush Work?
A smaller fish passes close by. The scorpionfish lunges, opens its enormous mouth, and draws the prey in within a fraction of a second. The contrast between the long wait and the sudden strike is what makes this feeding strategy so effective. [2]
Devil scorpionfish eat small fishes and crustaceans, usually feeding around dusk or at night. A daytime sighting may therefore show the waiting part of a routine that becomes more active as the light fades. [1]
Why the Name Scorpionfish?
The name refers to venomous fin spines. Along the back, spines within the dorsal fin have venom sacs at their bases. Pressure against a spine can force venom along its groove into an animal that bites or presses against the fish. [2]
This is a defensive system, not the method used to catch dinner. The mouth captures prey; the spines discourage other animals from treating the scorpionfish as a meal. [2]
It also explains why camouflage deserves respect. A fish that is hard to see can be accidentally touched or stepped on. Avoid touching the reef, putting your hands into crevices, or trying to handle a scorpionfish. [1, 2]
Where Devil Scorpionfish Spend Their Time
Look to the bottom rather than the open water. Devil scorpionfish are associated with reef surroundings, where they can wait on rock or coral and may move across sandy areas. Their ability to disappear against that background makes a sighting easy to miss even when a fish is nearby. [1, 2]
Unlike a conspicuous school swimming above the reef, a resting scorpionfish rewards patient observation from a respectful distance. Let your eyes adjust to shapes and textures without moving closer or disturbing the bottom.
Is It a Stonefish?
Large Hawaiian scorpionfishes are sometimes mistakenly called stonefish. The devil scorpionfish is a scorpionfish, and true stonefishes do not occur naturally in Hawaiian waters. That distinction does not make this fish safe to touch: its own venomous spines can cause a painful injury. [1, 2]
Two Different Ways to Be a Reef Predator
Compare the scorpionfish’s concealed, sit-and-wait approach with the very different silhouette of Kākū, the great barracuda. You can also meet another shelter-associated hunter in our snowflake moray guide.
A reef is full of different ways to find a meal. For nohu ʻomakaha, looking like nothing worth noticing is a valuable skill.
Meet the Fish Behind the Cards
Our Hawaiian Reef Fish Playing Cards pair watercolor illustrations with Hawaiian and English names. Meet the fish behind the cards, including the reef resident you might otherwise swim straight past.
Sources
[1] Maui Ocean Center: Devil Scorpionfish. Hawaiian and scientific names, camouflage, diet, feeding times, reef observations, and distinction from stonefishes.
[2] Waikīkī Aquarium: Devil’s Scorpionfish. Ambush feeding, camouflage, hidden warning colors, venomous spines, and avoiding accidental contact.