Its ventral fin, located on the fish's underside closest to its head, is entirely yellow. The frogfish has a different shape than the toadfish and you might say it is a little more proactive in the way it hunts for food. The frogfish is round with a mouth that resembles a trapdoor. Above that trapdoor is a dorsal spine that, when wriggled over the mouth, acts as a fishing lure for small fish and crustaceans. The frogfish's mouth can expand to 12 times its normal size in about eight milliseconds, enabling it to quickly gobble up prey mesmerized by the lure.
Frogfish species come in many different colors, including black and yellow.
Like the toadfish, it is able to camouflage itself and blend in with its habitat. Some frogfish may look like sponges, complete with patterns in the skin that resemble the holes found in sponges. Others may look like clumps of seaweed or seaweed-covered rocks. In addition to its coloring, the frogfish's gill openings are hidden behind its pectoral or side fins. That way, prey is not tipped off to its presence by outflowing water from the frogfish's gills.