A jawfish is a fish in the family Opistognathidae. The common name for these fish is a reference to their oversized heads and jaws that appear out of scale with the rest of their bodies. Jawfish are reef dwellers and they can be found in shallow reefs in oceans all over the world including the Pacific Ocean, Atlantic Ocean, and Indian Ocean, along with other bodies of water like the Gulf of Mexico. Divers and swimmers in these regions sometimes encounter these shy fish, if they are patient enough to wait for them to emerge.
Superficially, these fish resemble blennies, another type of tropical fish. Like blennies, jawfish are popular as aquarium pets. Some species are very expensive, such as the blue spotted jawfish, and they can become showpiece species for an aquarium. Jawfish are relatively hardy and easy to care for but they do have some special environmental requirements that must be met in order to stay healthy.
In the wild, the fish create burrows, moving rocks and other debris to do so. In an aquarium, they need to be provided with adequate substrate to burrow deeply, along with rubble and debris to support and camouflage the burrow. If they are not provided with materials, they can disturb everything at the bottom of an aquarium attempting to build homes for themselves. It is important to provide the fish with mixed building materials including debris like chunks of corals.
The jawfish will hover over its burrow or lurk just inside waiting for prey to pass. The fish eat a variety of small organisms that drift past in the water and can be fed in captivity using a number of different commercial preparations. When startled or frightened, the fish dart back into their burrows and conceal themselves until they think the threat is over. They can also become territorial. If they sense an invader, they may spit rocks and other debris to scare the intruder away from their burrows.
These saltwater fish are mouthbrooders. When eggs are laid, the male incubates them in his mouth to protect them from predators, periodically swishing the eggs through the water to aerate them.
Jawfish are brightly colored and they tend to be shy. They will hide from more aggressive fish and it is important to keep docile species with them in an aquarium environment to avoid stressing them. Aquarists enjoy keeping jawfish for their bright colors and interesting antics.