The brutish-looking bottom-dwellers Sepulcro and Papilio are teleost ambush feeders. Lying concealed in the silt-filled waster of the riverbed, the broad anglerfish relatives will wait for small prey, usually tiny schooling fellow ray-finned fish, to swim within reach. With a single sweep of the tail, huge mouths open wide, they will surge forward, swallowing everything in the immediate water with a single enormous bite.
- Sepulcro, Sepulcrostium malus (4-5 feet long). The Sepulcro is capable of an impressive gape of the mouth. Even other bony fish or other aquatic animals close to its own size are sometimes taken, the stomach being expandable to admit very large prey.
- Papilio, Papiliomonstrus opico (4-5 feet long). The elaborate Papilio is easily distinguished from the similar-habited Sepulcro by its array of fanlike lobes and fins. In most respects the ray-finned fish resembles its competitor, though it tends to favor invertebrate prey over weaker bony fish. In the breeding season males will engage in graceful displays of their wide fins to impress females as potential mates. The broad fins are also used to stir up bottom muck in which the fish will conceal itself and await the approach of prey.