Mexican Jawfish

About

The Mexican jawfish (Opistognathus mexicanus) is a fascinating burrower native to Mexican waters. Like other members of the jawfish family, it is built around one of the most recognizable behaviors in the hobby: excavating and maintaining a burrow, which it rarely strays far from. That oversized mouth is not just for show. It is the primary digging tool, used to shovel substrate and, famously in the jawfish world, to mouthbrood eggs. Males will carry a clutch of eggs in that cavernous jaw until they hatch, refusing to eat for the duration. In the aquarium, Mexican jawfish do best with a deep, sandy substrate that allows them to dig properly. Take that away and they become stressed and restless. They are generally peaceful toward unrelated tankmates, but can be territorial with their own kind unless the tank is large enough for each fish to establish its own burrow territory. Care is rated at intermediate, largely because their burrowing needs and sensitivity to water quality require a keeper who has moved past the basics. Given the right setup, though, they are endlessly watchable fish that spend their days hovering at the burrow entrance, ready to duck inside at the first sign of trouble.