Species Profile: Opistognathus rosenblatti (Bluespot Jawfish)

Beautiful, exotic, unique, finicky, heart breaking. These are just a handful of words that describe the bluespot jawfish (Opistognathus rosenblatti).

The bluespot jawfish, also called blue spotted jawfish, is found on the eastern coast of the Pacific Ocean and in particular the Gulf of California (Sea of Cortez). The waters in this area are somewhat cooler than waters where most tropical fish are collected, and the bluespot jawfish is typically found at deeper depths. Understanding these two aspects of their habitat is critical to provide the proper aquarium environment for them to thrive.

Blue Spot Jawfish

A typical jawfish dwelling consists of near vertical hole dug into the substrate that is surrounded by small rock rubble and various shells. However, the burrow can also be more horizontal if the underlying substrate is too hard, but crevices are present. The jawfish will stay in its burrow most of the time, venturing out only to catch nearby food or to find more items with which to decorate its burrow.

But these fish pose a serious challenge to even the most experienced aquarium hobbyist. For one, the tank must have a sand bed that is at least four inches deep, consisting of somewhat larger grain sand. Finer sand can be used, but the jawfish will move a lot of sand in order to construct a solid burrow. This is a trivial challenge, but a requirement that if often overlooked. In addition to a deeper sand bed, pieces of rock rubble will also need to be provided so that the fish can surround its burrow the rock and feel more at ease. At night, the jawfish will even cover its burrow with a piece of rubble so that no intruders can disturb it.

A slightly more serious, but still avoidable challenge is temperature control. As stated earlier, the bluespot jawfish is found in the colder waters of the Sea of Cortez. Most reef tanks hover in the 78-80 degree Fahrenheit range, but typically fluctuate several degrees a day and can easily reach 84 degrees. These temperatures are a few degrees too high for the bluespot jawfish, but can easily be remedied by using a chiller or fan on the tank to keep the temperature in check. Bright lighting doesn’t seem to be much of an issue for this jawfish, except that brighter light usually equals more heat in the tank.

Blue Spot Jawfish in Reef Aquarium

Photo Provided by the Author

One real problem with bluespot jawfish is disease. These jawfish are particularly sensitive to a brooklynella-like infection (typically associated with clownfish) and the mysterious Blue Spot Jawfish Disease. If a blue spot is infected with brooklynella, there is really no hope left for it. The fish will quickly deteriorate and die withing 24 hours or less. The jawfish will show signs of peeling skin and color loss all over its body, and it will refuse to eat. It may or may not wander around the aquarium, but it will most certainly leave its burrow and die. It is very painful to watch as there is virtually nothing you can do to save it at this point.

Shipping is a very serious hurdle for these fish to overcome. Blue spots, like all jawfish, are terrible shippers and are easily stressed out by being caught. They typically arrive at a fish store and quickly die. I’ve seen a store get in ten blue spot only to have them all die in less than two days. The stress of shipping doesn’t end when the fish gets into an aquarium. They take a while to settle in and get comfortable, and will jump out of nearly every tank, so some form of cover is recommended during the introduction period.

This gorgeous fish is tough to get, and even tougher to keep alive. But once established, the blue spot jawfish is an absolutely stunning addition to the aquarium and will have the most personality of any other fish in the tank. It will dig holes and defend them by flaring their gills in order to appear larger. They are not picky eaters, and will consume most frozen foods like brine or mysis shrimp. The blue spot can be a very expensive fish, exceeding $200 in some cases. So, prepare for the fish appropriately and be sure to do further research before you purchase.

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