Longtooth snake eel

Where they come from

Longtooth snake eels (Yirrkala macrodon) are Indo-Pacific fish that spend their lives hugged up to the bottom in sandy or rubble zones. Think slopes near reefs, silty sand, and places where a fish can vanish in a heartbeat. They are built for burrowing and ambush, not for cruising around the tank like a tang.

In the hobby they show up rarely, and most of the ones you see are wild-caught. That matters because they can arrive stressed, beat up around the mouth, and not interested in whatever food you wish they would eat.

Setting up their tank

If you try to keep this eel like a "normal" reef fish, it will go badly. You are basically setting up a secure burrowed predator tank with reef-like water quality. The eel should have a place to disappear completely, and the tank should be built around preventing escapes and injuries.

• Tank size: I would not do under 75 gallons, and 125+ is a lot less stressful once the eel settles in. They use floor space more than vertical space.
• Substrate: fine sand, deep. Aim for 4-6 inches if you can. Coarse crushed coral will rub them up when they burrow.
• Burrows: give them at least one tight tube hide (PVC works) buried under the sand with only one entrance showing. Add a couple rock-supported caves too, but keep rocks on the glass, not on the sand.
• Flow: moderate. You want oxygen and clean water, but not a sandstorm that keeps collapsing their burrow.
• Filtration: heavy. These are meaty-food fish and they make meaty waste. Skimmer, good mechanical filtration, and regular water changes are your friend.
• Lid: tight, weighted, and gap-free. Tape over cable cutouts if you have to. They can and will test every opening.

Lighting is for you, not for them. They do not need bright lights, and too much light with no cover can keep them hidden and skittish. If you want to actually see the eel, add plenty of shaded areas and let the front of the tank stay calm and predictable.

What to feed them

They are carnivores and they like substantial food. In the wild they go after small fish and crustaceans. In a tank, you want them on marine meaty items that are the right size and not too messy.

• Good foods: pieces of shrimp, squid, scallop, clam, marine fish flesh (sparingly), and quality frozen carnivore blends.
• Training tool: feeding tongs. Long ones. You want your fingers nowhere near a feeding response.
• How often: adults usually do great on 2-3 feedings per week. Newly imported or thin eels may need smaller meals more often until weight comes back.
• Supplements: soak in a vitamin/HUFA supplement occasionally. It helps with long-term condition, especially if you lean on shrimp and squid.

A trick that works: feed after lights are down or in dim light, and keep the room calm. If the eel is new, offer food near the burrow entrance and be patient. If you poke at it or rearrange the tank every day, it will just keep sulking.

How they behave and who they get along with

Most of the time you will see a head and some neck, or nothing at all. They are ambush predators. They are not "mean" in the way a triggerfish is mean, but anything that fits in their mouth is food, and they have a big mouth.

• Tankmates that usually work: larger, sturdy fish that do not sleep on the sand and are not small enough to be eaten (bigger wrasses, tangs, rabbitfish, some angels).
• Tankmates to avoid: small fish, gobies, blennies, small wrasses, dartfish, and anything that hangs around the bottom at night.
• Inverts: ornamental shrimp and small crabs are a gamble at best. Snails and larger hermits can go either way depending on the eel and hunger level.
• Other eels: doable only in big tanks with lots of hides, and even then you may see competition. Do not mix with similarly shaped burrowers unless you are prepared for problems.

They can also spook and launch backwards, which is another reason sand and a clear burrow route matter. Sharp rock edges and narrow rock crevices are where they get scraped up.

Breeding tips

Real talk: you are almost certainly not breeding this species in a home aquarium. Like many eels, their larval stage is planktonic and weird (leptocephalus-type larvae), and getting a pair, a spawn, and then raising larvae is beyond what most of us can do at home right now.

If you keep one long-term in great shape, that is already a win with this fish. Focus your energy on stable water, safe housing, and consistent feeding.

Common problems to watch for

• Refusing food after purchase: very common. Give it a secure burrow, dim periods, and offer smelly foods (clam, squid). Do not chase it with tongs.
• Mouth and nose abrasions: usually from rough substrate, glass surfing, or squeezing into rockwork. Fine sand and a proper tube hide prevent a lot of this.
• Jumping/escaping: almost always a lid issue or a startle event (sudden lights, loud bang, aggressive tankmate).
• Parasites and infections: wild fish can bring flukes and bacterial issues. Quarantine is hard with a burrower, but even a simple QT with a sand tray or buried tube helps.
• Water quality swings: heavy feeding can spike nutrients fast. Skim wet, change socks/pads often, and do regular water changes.

One more thing people miss: overflows and powerheads. Cover pump intakes, and block overflow entrances with a guard that does not have eel-sized gaps. A snake eel exploring at night can end up somewhere you never intended.