Oddball Ogcocephalus
Ever wonder if it would look like someone crossed an Anglerfish and a Flounder? Us too. Our guess is that this hypothetical franken-fish would look uncannily like Ogcocephalus corniger, which you may (or may not) recognize by the more common name, Walking Longnose Batfish. While it does walk, and does have a long nose, it certainly bears no resemblance to any of the other fish called “Bat,” and is unlikely in the extreme be called upon to fight the villains of Gotham. This fish acts mostly like an Angler, living on the bottom and walking / running about. They also have an esca, which is the little “lure” they use to tempt small fish into getting close enough to snack on. Though the WLB can retract their esca entirely into their head, a trick that Anglers haven't worked out. This flat(ish) fish will also take advantage of its low profile and partially bury itself in the sand too, not unlike a Flounder.
With a name like Walking Longnose Batfish, it is no surprise that this fish is a bit of an oddball, a term of endearment we use for the strangest of fish suitable for aquariums; this term is generally saved for fish that look weird, act weird, or both, and WLB's are definitely both. It really only has this one name, though the “Walking” portion is often dropped. Throughout the Spanish speaking portions of the Americas, it is known as Pez Diablo Narizon, or Big Nose Devilfish, a name we can also get behind.
Regardless of the name you give it, these are cool fish. They're native to the Caribbean, and eastern Atlantic as far north as the Carolinas, and as far south as Turks and Caicos, perhaps further. While generally collected in water less than 100 feet deep, they have been observed as deep as 750 feet down. They are ambush predators (obviously) that will entice small fish and inverts close enough to them to be eaten. The reason this works is a combination of being able to hide well (mostly covered with sand) and fishing well, with their (previously referenced) esca.
It logically follows that this fish would do well with a sand bed, and it doesn't need to be that deep, an inch or two will suffice. Honestly, they don't really require it, but they'll use it, and why not get the best display you can for your fish! So, for us, a nice sand bed anchors this display. WLBs will get ten inches long or so, albeit very slowly. A truly huge specimen might make it to a foot long, but still, they aren't wildly active, so you could keep one in a tank as small as 75 gallons, but they'd be better in 180 for the width and length. There doesn't need to be much in the way of rocks, and what rockwork exists should leave plenty of open sandy space for your Walking Longnose Batfish to hide and run around and generally do its thing. Lighting is immaterial, though they may be bolder initially if the lighting is subdued. WLBs are super unlikely to go anywhere near the surface of the tank, so a cover is generally not necessary. Ogcocephalus corniger is a messy eater, so filtration should be strong and water changes shouldn't be neglected.
On the topic of eating, these are very fun fish to feed. They're used to angling for live food, and ideally, you'd allow this to continue to happen, through the use of live (clean and gut loaded) feeder fish. Raising a culture of salt acclimated Guppies or Mollies is perfect for this. You can feed your Mollies good food, like Nutramar Complete Pellets, and then feed those mollies into your display and give your WLB a nutritious, and fun to watch feeding experience! They'll also learn to take thawed foods, especially if you target feed them with a feeding stick. Things like Gamma Whole Fish are perfect for this. Smaller specimens will do well splitting these fish in two, or also utilizing smaller foods like the Gamma Chopped Mussel. Over time, they'll learn to take these foods without your target feeding them. If they have a large meal, once a day or once every other day is enough for smaller specimens and two to three times a week is plenty for larger specimens. They will usually also take feeder shrimp and earthworms without hesitation.
As you've likely deduced from this, Walking Longnose Bats are very likely to eat anything that is unwary enough to get close to them. Keep this in mind when choosing other fish for this display. If a tankmate is small and slow / unwary they will get eaten, not maybe, will. The WLBs are great fisher-folk. That being said, Ogcocephalus corniger is fine with larger fish, or fish that aren't going to go low in the water column and into their strike range. Avoid fish that are notorious pickers like Puffers and triggers as they could injure the Batfish by giving it some exploratory nibbles. We've seen no reason to avoid keeping them with corals, except for sand bed stuff that could get up-ended or covered with sand when the Batfish moves around or digs itself in.
Water quality wise the Walking Longnose Bat is a pretty hardy fish. Keep nitrates under normal reef tank levels and you won't have an issue. These fish like a steady pH that between 8.0 and 8.4, a specific gravity that's between 1.025 and 1.026 and a temperature between 70 and 78. All totally achievable goals by almost all aquarists. If you fit that description, and you're looking for an absolute oddball to put into your tank, give a long thought to Ogcocephalus corniger. There are few fish out there that can compete for pure weirdness or coolness of keeping. Ask your LFS about getting you one from Quality Marine today!