Wolf Eel: Not an Eel, and How to Identify One

A wolf eel is a wolffish — Anarrhichthys ocellatus, one of five species in the family Anarhichadidae — and the easiest way to prove it is the pectoral fins. Wolf eels have large pectoral fins set behind the head, the way an ordinary fish does. True eels have tiny fins there or none at all.

What gives the wrong impression is the body: a normal-looking front half that tapers into thick, muscular waves of tail, making it the most elongated member of its family.

Other identification points:

• Adults are grey with dark spots ringed on the back and sides
• Juveniles are bright orange, and the colour fades as they mature
• Males have notably thick jaws and a bulging forehead; females keep a narrower head
• The head is heavy and blunt, with visible front teeth even when the mouth is closed

If you photographed one on a dive in the Pacific Northwest and want to be sure it is not a true eel or an eelpout, photograph it and the app identifies it.

Wolf eels range across the North Pacific from northern Baja California to Kodiak Island, Alaska, and west to Russia and the Sea of Japan. They occupy rocky reefs and crevices from shallow water down to about 740 feet, and Aquarium of the Pacific notes records from much deeper still.

An adult coils into a cave or crevice and keeps only its head out, which is why divers usually meet one as a face in a hole. Once mature they are largely sedentary and defend that shelter.

The diet is hard-shelled. Wolf eels eat crabs, sea urchins, sand dollars, snails, abalone, mussels, clams and fish. The jaws do the work: strong canines at the front to grip, and heavy molars behind to crush shells and urchin tests. Juveniles start on copepods and zooplankton in open water before settling to the bottom and switching to fish and hard prey.

Wolf eels form strong pair bonds and mate for life. A male and female share one den and defend it together, often for many years, and divers who know a local reef can visit the same pair season after season.

Females begin reproducing around age seven and lay up to 10,000 eggs in a clutch. The female coils her body around the egg mass to hold it together, and the male wraps around her as an outer layer, so the eggs are protected twice over. The pair takes turns leaving to feed rather than abandoning the nest, and incubation runs roughly three to four and a half months before hatching.

It is an unusually large parental investment for a fish, and it is why a wolf eel den is a long-term feature of a reef rather than a temporary shelter.

A wolf eel has teeth built to crush urchins and will bite if cornered, handled or fed by hand, and a bite from an animal with that jaw strength is a serious injury. But wolf eels are not aggressive toward divers and are widely described as curious rather than hostile.

The sensible approach is the same as for any large reef animal: look, photograph, and do not reach into the den. Hand-feeding in particular teaches the animal to associate divers with food and creates exactly the situation where bites happen.

Anglers occasionally hook one from rocky ground. Cut the leader or unhook it with a long tool in the water rather than bringing the head near your hands.

Aquarium of the Pacific gives about 25 years as a typical captive lifespan, and reports one individual observed for twenty years. Wild longevity is not well documented.

Wolf eels are a signature animal of cold-water Pacific diving from California through British Columbia and Alaska, and they are common in public aquariums along that coast precisely because they are long-lived, sedentary and used to people.

On a dive, look for the head first. A grey, heavily jawed face in a crack at the base of a rock wall, usually with a second one behind it, is the standard sighting. A bright orange ribbon of a fish in open water near the bottom is a juvenile and often surprises people who only know the adults.

Both halves of the name are descriptive rather than scientific. Wolf refers to the heavy, wolf-like head and powerful jaws with long front teeth (Wikipedia), a trait of the whole wolffish family, Anarhichadidae. Eel refers only to the long, tapering body; as explained above, it is not a true eel.

Other names:

• Pacific wolf eel
• Wolffish, the family name
• Doctorfish, a name from Pacific Northwest Native American cultures (Wikipedia)
• Sea wolf, in some popular accounts

The scientific name, Anarrhichthys ocellatus, is the one that leaves no doubt.

Wolf eels are known for being calm and curious with divers. Monterey Bay Aquarium staff describe their temperament as the opposite of their fierce look, and say they are aggressive only toward other wolf eels. Wikipedia describes large wolf eels as curious and rarely aggressive.

Calm is not the same as safe to handle. The same Wikipedia article notes that they can inflict painful bites, and that a wolf eel can still bite even after it has been decapitated, a warning for anglers cleaning one. Enjoy them from a short distance and keep hands out of the den.

Wolf eel is edible, and Wikipedia describes the white flesh as sweet and savoury. It has a cultural history too: among some Native peoples of the Pacific coast, only healers were allowed to eat it, because it was believed to strengthen their healing powers.

It is not a commercial food fish. The Monterey Bay Aquarium says wolf eels are not targeted by fisheries but are often caught in traps. If one comes up as bycatch, check the current state or provincial rules before keeping it, and releasing it is always an option; the handling advice in the section on danger above applies.

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Every number names the organisation it comes from; where sources disagree we say so rather than pick one silently. Rules and advisories change, so treat the dates given here as the date we checked. If you find an error, tell us and we will correct it.