Longnose conger

Where they come from

Longnose congers (Bathycongrus wallacei) are the kind of eel you usually see mentioned in deep-reef and slope collections, not in everyday hobby talk. They are marine, secretive, and built for poking their face out of a hole while the rest of the body stays buried or wedged into rock.

That background matters because they do not behave like a "swimming eel". Think ambush predator that wants a secure den, low drama, and predictable food.

Setting up their tank

This is an expert fish for one main reason: keeping them is less about fancy numbers and more about preventing the two classic eel disasters - escape and starvation. If you can lock down the tank and get it eating reliably, you are most of the way there.

Go bigger than you think, not because they "need to swim", but because stable water and room for multiple den options makes everything easier. I would not bother below a 180 gallon for an adult-sized conger-type eel, and bigger is nicer if you want tankmates.

• Rockwork: build it like a cave system, not a tower. Wide base, lots of contact points, nothing that can topple if an eel wedges under it.
• Dens: PVC elbows or lengths of 2-3 inch PVC hidden in the rock are gold. Give at least two choices so it can relocate if spooked.
• Substrate: fine sand helps if it likes to dig. Avoid sharp crushed coral that can scrape the belly.
• Flow: moderate, with calmer pockets near the dens. Blasting the cave entrances tends to keep them stressed and reclusive.
• Filtration: heavy. They are messy carnivores and you will feel it in your nitrates fast.

Aim for normal reef salinity and temperature and focus on stability. These guys do not appreciate big swings, and once an eel goes off food it can be a pain to turn around.

What to feed them

They are predators. In my experience, the first month is about getting a consistent feeding response and making sure food actually reaches the eel instead of the cleanup crew.

• Best staples: chunks of marine fish (not freshwater feeders), shrimp, squid, clam, scallop, and other meaty marine foods.
• Good variety: rotate foods so you are not just feeding one thing forever.
• Avoid as a main diet: silversides every time (fatty and can foul water), and anything from unknown bait sources that reeks or looks off.

Use feeding tongs and present the food right at the den entrance. Once they learn the routine, they will usually poke out and grab. If you just toss food in, crabs, shrimp, and bold fish often steal it and the eel slowly loses weight.

Feeding frequency depends on size. Smaller individuals can eat smaller portions 2-3 times a week. Bigger eels do fine with a couple solid meals weekly. Watch body shape: you want a thick, muscular look behind the head, not a pinched neck or visible backbone.

How they behave and who they get along with

Expect a lot of "eel being an eel": hiding most of the day, head out at dusk, and a strong feeding response once it recognizes you. They are not typically out cruising like a snowflake eel.

Tankmates are where people get burned. Anything that fits in the mouth is on the menu eventually, and anything that harasses the eel can keep it from feeding.

• Safer tankmates: larger, confident fish that will not pick at it and are too big to be eaten (think bigger tangs, large angels, some triggers with caution).
• Risky: small fish, shrimp, crabs, and "cute" bottom dwellers. If you like your clean-up crew, you probably will not for long.
• Avoid: aggressive fin nippers and fish that wedge into the same holes (they turn dens into a constant fight).

Breeding tips

Realistically, breeding Bathycongrus wallacei in home aquariums is not a thing right now. Conger-type eels have complex life cycles with pelagic larvae, and we do not have a reliable hobby playbook for conditioning and raising them.

If you keep more than one, do it because you have a huge system and a plan, not because you expect a pair. Multiple eels often end up with territory issues unless the tank is enormous with lots of separate dens.

Common problems to watch for

• Escapes: the number one killer. Secure lids and block every gap, including overflows and back chambers.
• Not eating after arrival: common with shy eels. Reduce traffic around the tank, dim the lights, and offer food at dusk with tongs.
• Internal damage from rockwork: unstable rocks can crush or scrape them. Build rockwork like you are eel-proofing for digging and wedging.
• Poor water quality from heavy feeding: big carnivore meals can spike nutrients fast. Oversize the skimmer, run carbon, and do consistent water changes.
• Mouth and snout injuries: happens when they hit the lid or scrape against sharp rock. Smooth the den entrances and remove abrasive rubble.
• Parasites and shipping stress: observe for rapid breathing, excess mucus, flashing, and refusal to feed. Quarantine is tough with escape artists, but a dedicated, covered QT with PVC hides is worth it.