Elongate duckbill eel

Where they come from

Elongate duckbill eels (Saurenchelys elongata) are deepwater marine eels that spend a lot of their time down in the mud and rubble, poking that long snout around for small prey. They are not a reef flat, sunlit lagoon kind of fish. Think dim, quiet, and bottom-heavy habitat.

Most show up as rare imports and they are often stressed from collection and shipping. If you are looking at one at a store, the animal in front of you matters more than the name on the bag.

Setting up their tank

These eels are all about the bottom. Give them a tank that lets them burrow, feel secure, and hunt without being blasted by flow or bullied by hyper tankmates.

• Tank size: I would not bother under 75 gallons, and 120+ is a lot less stressful long-term because you can build a big sand zone and still have room for rockwork.
• Substrate: fine sand, deep enough to bury (3-6 inches). Skip sharp crushed coral. Their face and belly will pay the price.
• Rockwork: stable and on the glass, not sitting on sand that can shift. They will dig and undermine things.
• Light and flow: moderate flow that does not turn the sandbed into a snowstorm, and lower light or lots of shaded areas.
• Filtration: heavy on mechanical and biological. Feeding meaty foods means waste, and these guys do not live well in dirty water.

I have had the best luck giving them a couple of "starting burrows" - a short length of PVC half-buried under the sand and a shaded corner behind rock. Once they settle, they will make their own routes.

Water conditions

Keep salinity steady (around 1.025-1.026) and avoid big swings. Stability beats chasing numbers. They do not respond well to sloppy maintenance, and a stressed eel goes off food fast.

What to feed them

Plan on a predator-style diet. Most will not touch flakes or pellets. You are feeding with tongs, and you will probably be feeding after lights out.

• Good staples: thawed silversides (appropriately sized), pieces of marine fish, shrimp, squid, scallop, and clam.
• Best "first foods": live blackworms (if you can get them safely), live ghost shrimp acclimated to salt, or small live marine shrimp to kick-start feeding in a new arrival.
• Avoid: freshwater feeder fish (disease and fatty profile), and big chunky meals that stretch them out like a sausage.

Once they are eating reliably, smaller meals more often works better than one huge feeding. I usually aim for 2-3 times per week for an established adult, adjusting based on body condition and how active it is.

How they behave and who they get along with

They are secretive. A happy one is often a half-buried snout and eyes at dusk, then a slow, deliberate cruise along the sand. Do not expect a "display" eel that is always out front.

Anything shrimp-sized is food. Anything fish-sized that sleeps on the bottom is a gamble. Their mouth is not as massive as a big moray, but they are still an eel with eel instincts.

• Good tankmates: calmer midwater fish that will not pick at the eel or outcompete it for food (bigger cardinals, some anthias if you can manage feeding, larger peaceful wrasses).
• Risky: small gobies, blennies, firefish, small cardinals, and bottom perchers that nap in the sand.
• Avoid: aggressive triggers, large puffers, and nippy angels that treat the eel like a chew toy.

Breeding tips

Realistically, breeding this species in home aquariums is not a thing right now. Deepwater eels have complicated life cycles and larval stages (leptocephalus larvae) that are extremely hard to rear even in professional setups.

If you ever see two together, do not assume you can pair them. A second eel in the same sandbed can mean stress, competition for burrows, and missed meals unless the system is huge and structured for it.

Common problems to watch for

• Not eating after arrival: very common. Give it sand to bury, keep the tank quiet, and start with small, smelly foods at night.
• Scrapes and snout damage: usually from rough substrate, unstable rock shifting, or panicked dashing into glass. Fine sand and secure rockwork prevent a lot of this.
• Parasites (especially after import): heavy breathing, flashing, excess slime, and refusal to eat. This is where a sand-friendly QT pays off.
• Starvation from competition: looks like a thin neck/shoulder area and a "pinched" body even if it is still coming out sometimes.
• Escape attempts: often triggered by poor water, harassment, or too much light and nowhere to hide.