Jawfish (Opistognathidae) live in a small hole, and therefore require a deep sand substrate.
When given the right conditions, one has a good chance for success with keeping them, as Jawfish are fairly easy and hardy. One should not however add them to an aquarium with aggressive fish or others which dig in the sand, unless there is enough space.
Jawfish are known for hopping out of the aquarium, even through the smallest holes. This occurs when they do not have enough time to find a hole before the lights are turned off, so one should try to make a hiding place for them, when newly introduced.
Jawfish will sometimes gasp for air at the surface until they have made a hole. If this behaviour continues, it could indicate that the surroundings are not suitable or that the Jawfish is being disturbed by the other fish, this must be solved in order for the fish to survive.