Duckbill eel

Where they come from

Duckbill eels are deep-slope sand burrowers from the Indo-West Pacific. Think soft, silty bottoms well offshore. They spend most of the day buried with just that long snout poking out, then go hunting after dark. That lifestyle explains a lot of their quirks in a home tank.

Tank setup

Plan for a big footprint and a deep, soft bed. A 6-foot tank (180 gallons or more) gives them room to choose a burrow spot and not feel boxed in.

• Substrate: 6-8 inches of fine, sugar-sized aragonite. No crushed coral. They rub their skin and mouth a lot while burrowing, and sharp stuff leads to sores.
• Burrows: Bury 2-3 inch PVC elbows or a U-shaped length with both ends exposed. Sink them fully under the sand so the eel can dive in and feel secure.
• Rockwork: Build on the bare bottom first, then add sand. That way nothing collapses when the eel tunnels.
• Lid: Tight cover with every gap taped or mesh-screened. Overflow teeth, cable cutouts, even return nozzles get blocked. They are world-class escape artists.
• Lighting: Keep it dim or at least provide heavy shaded areas. They relax a lot more with subdued light.
• Flow and gas exchange: Moderate flow, high oxygen. Run a strong skimmer and point some surface agitation at the top for good gas exchange.
• Temperature and chemistry: Slightly cooler than a typical reef. Mine settled in at 70-73 F with a chiller. Salinity 1.023-1.025, pH around 8.0-8.3, ammonia and nitrite 0, keep nitrate low.
• Quarantine: A dim QT with a buried PVC hide. Drip acclimate slowly and give them peace and quiet for the first few days.

What to feed them

They are ambush predators. Getting a new one to eat is 90% about timing and presentation.

• Starter foods: Live saltwater ghost shrimp or small shore crabs get them going. Once they strike reliably, switch to frozen.
• Staples: Silversides, squid strips, raw prawn, lancefish, and marine fish fillet. Soak in vitamins now and then.
• Feeding trick: Use long tongs. Wiggle the food at the burrow entrance after lights out. Keep still for 30-60 seconds between wiggles. They watch and wait.
• Schedule: 2-3 modest meals per week. Big meals sit heavy and foul water.
• Avoid: Freshwater feeder fish and goldfish. They are risky disease-wise and packed with thiaminase.

How they behave and who they get along with

Shy by day, curious at night. They cruise like a ribbon, then reverse back into the burrow if spooked. Not aggressive, but very predatory.

• Safe tankmates: Medium to large fish that are calm and not nippy. Tangs, rabbitfish, larger cardinals, and some peaceful wrasses tend to ignore them.
• Risky tankmates: Triggers, puffers, and big wrasses. They nip at fins and faces and will harass the eel.
• Food, not friends: Small fish and all ornamental shrimp or crabs are on the menu once the eel settles in.
• Other eels: Best kept single. Burrow squabbles happen in anything but huge systems.

Breeding tips

These are oceanic spawners with a leptocephalus larval stage. No documented home-aquarium breeding that I know of, and pairing is guesswork. Treat every specimen as a long-term single fish project.

Common problems to watch for

• Refusing food: Very common early on. Keep the room dark, reduce traffic, and try live ghost shrimp at night. Once they eat 2-3 times, they usually switch to tongs.
• Mouth abrasions: From sharp substrate or rough PVC edges. Use fine sand and sand the PVC lips smooth.
• Escape attempts: Especially the first month. Tape and mesh every gap. Weight the lid.
• Import stress and barotrauma: Deepwater fish can arrive wobbly or with buoyancy issues. Low light, high oxygen, and minimal handling help. Some never recover; pick a robust, alert specimen if you have a choice.
• Medication sensitivity: Like other eels, they do poorly with copper and strong formalin doses.
• Internal parasites: Stringy poop or weight loss despite eating. Food-soaked praziquantel or metronidazole in a separate tank has worked for me.