Frogfish, Antennariidae

Antennariidae is a family that holds forty-eight species of frogfish, which are actually a type of anglerfish that reside in the tropical and sub-tropical waters of the Indian Ocean, Red Sea, Pacific Ocean, and Atlantic Ocean. Most frogfish species can be found along the ocean floor near coral or rock reefs, although the Brackishwater Frogfish can be found in both salt and fresh water and the Sargassumfish can travel as far as Norway on the drifting sargassum on which it resides. Some of the species within this family include the longlure frogfish, the painted frogfish, the scarlet frogfish, and the warty frogfish.

Frogfish are stocky and reach an average length between one and fifteen inches and their bodies are often bare of scales, holding bumpy spinules instead. There is a vast difference between the coloration of frogfish species, making it difficult to distinguish between them, but many are brightly colored and have markings that allow them to blend in with the coral around them. Instead of displaying a dorsal fin, frogfish have a front fin that is known as an illicium, which is typically striped and is most often topped with a lure. The lure varies between species, but it is easier to recognize individual species using the lure rather than body color.

The unique appearance of frogfish serves as a defense mechanism and a means of catching prey. Some species resemble coral, sea sponges, or sea urchins while others resemble the sea floor. Many species are able to change their color, although it is unknown if this is a defense mechanism. Frogfish do not often move, but they will move in order to hunt food. Once prey is located, the fish will move within seven body lengths while waving its lure, which can resemble other creatures like shrimp or simply be a lump. Sometimes the fish will stalk its prey, but it can also wait for its prey to come within range of its mouth. Once it is in range, the fish will open its mouth up to twelve times its normal size and suck the prey into the mouth at speeds as small as six milliseconds.

The mating habits of frogfish have not been completely studied, as they are typically solitary in nature, and there have been fewer observations in the wild than in aquariums. Most species have been found to partake in free-spawning, which occurs when females lay up to 180,000 eggs, followed by the fertilization from males. Females will swim up to the surface and lay their eggs, which is sometimes encouraged by the male, and after the males fertilize the eggs they must quickly leave or risk being eaten by the larger females. A few species are known to lay their eggs on rocks while others are known to guard their eggs.

Members of the Antennariidae family can be seen in aquariums around the world, although they are difficult to maintain. It is common for captive frogfish to become very fat or refuse to eat at all, and because they can consume prey up to twice their own size, it is best to keep them alone. They will often times lose their bright coloration when placed in dull tanks. Breeding in captivity has been observed, but raising the young frogfish is difficult due to their specialized diets and their chance at becoming prey for other fish.

Image Caption: A spotfin frogfish waiting amid the coral. Credit: Izuzuki/Wikipedia  (CC BY 2.5)