The jawfish are masters of architecture. They use their large mouths to scoop sand from the seabed and then spit it out to one side. They continue to dig until they have created a vertical tunnel with a chamber at its end. The jawfish will shove rubble around the burrow entrance and lodge larger bit of debris along the length of the tunnel to give it more structural integrity. The yellowhead jawfish (Opistognathus aurifrons) is one of the most common members of the family and is not only interesting to watch, it is also very attractive. It is also a very affordable fish for North American aquarists.
Difficulty: If certain environmental requirements are met, the yellowhead jawfish is not a difficult species to keep. There are a few pitfalls with keeping the yellowhead jawfish that will be discussed below.
Physical description: The yellowhead jawfish is a slender fish with long pelvic fins. The body and fins are pale blue, while the head is lemon yellow. Jawfish populations from various locations exhibit some chromatic differences. Floridian specimens lack black spots on the chin and tend to be more bluish. Yellowheads from other locations may or may not have the black chin spots, and are more yellow and less blue. The yellowhead jawfish reaches a length of 4 inches. It is sometimes referred to as the pearly jawfish.
Range: Opistognathus aurifrons is found along the coast of South Florida and the Bahamas south to northern South America. The yellowhead jawfish has been reported from depths of 10 to 165 feet on sand patches at the edge of fringing reefs, on sand flats and sand slopes. The yellowhead jawfish is a zooplankton-feeder. It hovers above its burrow opening and picks off passing zooplankton. It will back into its burrow if it detects a potential threat and will dive head-first into the entrance if the danger is more immediate.
Compatibility: The yellowhead jawfish is a very peaceable fish that rarely bothers its tankmates. It can even be housed in groups. A colony of four to six yellowhead jawfish can be kept in a 55-gallon aquarium and makes for a fascinating display. However, if your captive jawfish colony is too large, a member or members of the group may be excluded by conspecifics from creating a burrow. You will have to remove the subordinate fish or it will jump out (if it can find a hole in the top) or hang-out in the corner of the aquarium until it perishes. The jawfish is sometimes picked on by dottybacks, damsels, pygmy angelfish and sand perches. Once it has built its burrow, it has a place to hide from potential bullies. It will also be preyed upon by moray eels, frogfish, scorpionfish and larger triggerfish.
Aquarium conditions: The yellowhead jawfish requires an aquarium that has a deep sand bed (at least 6 inches in depth). The substrate should consist of crushed coral, along with plenty of bits and pieces of shell, snail shells and coral fragments. The more heterogeneous the substrate, the easier it is for the yellowhead jawfish to create its burrow along with the terminal cavity (a cavern at the tunnels end). It is a good idea to place some flat pieces of live rock over depressions in the sand to help a newly introduced jawfish find and build a home. Keep the yellowhead jawfish at a pH of 8.1 to 8.4, specific gravity of 1.019 to 1.025 and a water temperature of 74 to 82 degrees Fahrenheit.
Care considerations: The yellowhead jawfish is an expert jumper. It is especially prone to leaping when first added to the aquarium. If a yellowhead jawfish cannot find a suitable place to dig its burrow and has not had enough time to do before the light is extinguished its first night in its new home, it is more likely to jump out. A night light may help prevent jumping. A new Opistognathus aurifrons will also swim along the water’s surface with its head bobbing in and out of the water if it cannot find a good hiding place.
Breeding: If you keep a colony of jawfish, there is a good chance they will spawn. They orally incubate the eggs. After the female yellowhead jawfish deposits eggs and the male fertilizes the eggs, the male takes the eggs in his mouth until the eggs hatch, at which time he spits the larvae in the water, and they enter the water column. Yellowhead jawfish eggs hatch in seven to nine days.