Mysterious Jawfish Behavior

[spd3001]

Last May I bought a Pearly Jawfish (Opistognathus aurifrons) that was 2-3 inches long for our display tank (24" x 24" and 36" high). It was the first addition other than a few small sps corals. The tank has a deep sandbed (6" to 7" deep) with all the rock structure epoxied to a pvc grid buried in the sandbed to prevent collapses that might injure jawfish or gobies. Everything has been going well with the water chemistry staying steady and the fish and corals doing well. Then about a month ago, the jawfish stopped closing the door to its burrow at night and could only occasionally be seen, just its head in the opening and no more hovering above the opening. After 2 or 3 days of this behavior, it disappeared and was not seen again. Yesterday I found the burrow filled in with loose sand and I assumed my tiger pistol shrimp/watchman goby had filled it in as they're pretty active in closing and opening burrows all over the place. But about thirty minutes ago I went to feed the tank its evening round of mysis shrimp and there it was. The no-show jawfish was back and hungry for its mysis shrimp! It's body and fins look great, no obvious injury. So it's been missing and assumed gone for almost a month. I mean I held out hope since there was no ammonia spike but I really did not expect to see it again.

Is anybody familiar with this kind of behavior or have a theory about was going on? Was it perhaps a tiger shrimp-jawfish standoff? The only other occupants of the tank are two Banggaii Cardinalfish, two peppermint shrimp, a blue tuxedo urchin and a few Astrea and Cerith snails. There are some bristle worms in the tank, mostly in the 2 to 3 inch range in size. No clue here as to what was going on but we're thrilled to have Jack the jawfish back.

 

[spd3001]

I just reread my post and realized that it didn't really give an idea as to how long the jawfish was missing. It was almost a month between the time it disappeared and yesterday when I saw that its burrow had been filled in. Today at dinnertime it was back and wanting its mysis shrimp.

 

[i cant think]

To me that’s just a Jawfish doing more to it’s burrow, my yellow head Jawfish I had would disappear for weeks just to do more work on it’s burrow (it was a 2-3” sand bed). It’s curious behaviour for sure!!