When people ask me whether eels are dangerous, the honest answer is that eels are much more likely to hide from you than bite you. Morays have poor eyesight, a superb sense of smell and a strong instinct to stay in their holes. The bites that do happen almost always follow the same script: a diver, snorkeler or fisherman puts a hand where an eel lives, or waves food in front of one, and the eel does what any animal with a mouth full of teeth would do. This page explains why eels bite, what the wounds look like, why they go bad so easily, and what to do if it happens to you.

Why do eels bite?

Fear, territory and food: the same three reasons as most animals.

A moray’s hole is its home, its ambush point and its refuge from groupers, barracuda and sharks. Anything that comes into that space uninvited is a threat. A hand pushed into a crevice to steady yourself, pick up a lobster or retrieve a dropped torch looks, to a moray, like an intruder, and the eel bites to drive it off.

The second common cause is feeding. On some reefs, eels were hand-fed by dive guides for years, and those eels learned to associate divers with food. They come out of their holes, swim up to people and snap at anything that looks or smells like a snack. Because morays see poorly and hunt mostly by smell, a finger that smells of fish is easy to mistake for one. Many of the worst moray injuries in the medical literature came from feeding situations like this. Spearfishermen face the same problem when an eel is drawn to speared fish on a stringer.

Freshwater eels and congers bite for the same defensive reasons, usually when they’re being handled after being caught. An eel thrashing on the deck of a boat or on a riverbank is frightened and will bite whatever holds it.

What does a moray eel bite look like?

A ragged set of punctures and tears rather than a clean cut.

Moray teeth are long, sharp and angled backward, which helps them grip slippery fish. When a moray bites and you pull away, those teeth rake through the skin and the tissue beneath it. A typical moray bite mark is a crescent of deep puncture wounds, often with tears between them or flaps of skin pulled loose. On the hand, where most bites land, the teeth can reach tendons, nerves and blood vessels, and some victims have needed surgery to repair them.

Morays can also hold on. They’re not built to let go quickly, and the instinct to yank your hand free is part of what makes the wound worse. In most reported cases the eel releases on its own within seconds. Bites from small morays and freshwater eels look much less dramatic: a row of small scratches or punctures that may bleed but usually heal well if kept clean.

Why eel bites get infected

Seawater, reef bacteria and deep puncture wounds are a bad combination.

Any wound made in seawater is exposed to marine bacteria, and puncture wounds are the hardest to clean because the bacteria are pushed deep into the tissue. Doctors who treat marine injuries pay particular attention to Vibrio species, which live naturally in warm coastal water and can cause fast-spreading infections, especially in people with liver disease, diabetes or weakened immune systems. Other bacteria from the eel’s mouth, the reef and the skin can also cause trouble. Teeth sometimes break off in the wound, which is another reason a doctor may want an X-ray.

Because of that infection risk, medical teams often clean moray bites thoroughly and leave them partly open rather than stitching them tightly, and they usually prescribe antibiotics chosen to cover marine bacteria. That decision belongs to a doctor, which is why I’d treat any moray bite that breaks the skin as a reason to see one, even if it looks small.

First aid for an eel bite

Get out of the water, stop the bleeding, clean it, and get it checked.

1. Don’t yank. If the eel is still holding on, try to stay calm. Pulling against backward-curved teeth makes the wound worse, and most eels let go quickly.
2. End the dive safely. Bleeding underwater looks dramatic but ascend at a normal rate and make your safety stop if you can. A rapid ascent is a bigger danger than the bite.
3. Control bleeding. Apply firm, direct pressure with a clean cloth or dressing and raise the limb.
4. Clean the wound. Rinse well with clean fresh water (bottled or tap) and mild soap, and remove any visible debris. Don’t scrub deep punctures aggressively.
5. Cover it. Use a clean, loose dressing.
6. See a doctor. Mention that it was a marine animal bite. Ask about tetanus protection and antibiotics, and whether stitches are appropriate.
7. Watch for infection. Increasing redness, swelling, heat, pus, red streaks, fever or severe pain over the next few days need urgent medical attention.

This is general information, not medical advice. If a bite is deep, bleeding heavily or on the hand or face, treat it as an emergency.

Are eels dangerous to humans?

Some can injure you, but none of them hunt people.

The only true eels that cause regular injuries are morays, and even with morays, serious bites are uncommon given how many divers swim past them every day. The danger people tend to forget is eating them. Large morays, especially the giant moray, can carry ciguatoxin from the reef food chain, and ciguatera poisoning can cause weeks of nausea, tingling and temperature-reversal symptoms. That’s covered on our page about eating eel.

How I avoid eel bites on a dive

A few simple habits make a moray bite almost impossible.

Morays are regulars at many of the sites in my dive guides. The Key Largo dive guide lists green morays on Molasses Reef, the Key West guide lists morays on the Cayman Salvage Master wreck, and the Roatan guide has them on El Aguila. These are the rules I follow and recommend:

• Keep your hands to yourself. Never reach into holes, under ledges or into wreck openings you can’t see into.
• Don’t feed eels, and don’t dive with operators who hand-feed them. Fed eels are the ones that bite.
• Watch your buoyancy. Good trim keeps your hands and knees off the reef, which protects the coral and keeps your fingers away from eel dens.
• Don’t carry speared fish or bait near reef holes.
• Give the eel an exit. If a moray comes out of its hole, back off slowly. It wants to get away from you more than you want to get away from it.

If you follow those rules you can get your mask within an arm’s length of a moray for a photo, and it’ll do nothing but breathe at you. For more on behaviour, see our guide to reef eels.

Eel bites while fishing and handling eels

Outside of diving, most eel bites happen on boats, docks and riverbanks.

Anglers catch eels by accident all the time. Congers take fish baits on wrecks and piers, morays grab baits dropped near reef ledges, and American and European eels are caught on worms in rivers and estuaries. A hooked eel is strong, slippery and frightened, and it will twist, wrap around a line or an arm and bite at whatever is holding it. Moray and conger bites in these situations can be as bad as any diver’s injury, because people tend to grab the eel near the head to unhook it.

The safer approach is not to handle the eel at all. Cut the line close to the hook if you can’t remove it easily with long-nosed pliers or a dehooking tool, and keep your hands well away from the head. Eels can stay active for a long time out of water, and even an eel that looks dead can still bite reflexively. Wet towels or gloves help with freshwater eels, but no glove will stop the teeth of a large moray or conger.

The same caution applies to anyone cleaning eels. Raw eel blood contains a toxin that can irritate cuts and eyes, so rinse well and avoid getting blood into an open wound. That toxin is destroyed by cooking, which is part of the reason eel is always cooked before it’s eaten.

Why moray bites make headlines

A few dramatic cases have shaped how people see eels.

Medical journals and news stories describe a handful of severe moray injuries each decade, mostly to the hands and fingers, and nearly all involve feeding, spearfishing or deliberately handling the eel. Those cases are memorable because the injuries are ugly, but they’re a tiny fraction of the encounters that happen every day on reefs around the world. Thousands of divers photograph morays at a few centimetres’ range without incident. When you weigh the risk, a moray is far less dangerous than a jellyfish sting, a coral cut or a careless ascent.