URGENT!! Diamond watchmen goby flailing around?

[Bugenar]

Just picked up a diamond watchmen goby yesterday and added it to my 65 gallon, all was well, there was a few aiptasia on one side of the bed but otherwise it just avoided it and was fine. But this morning I woke up to see the goby flailing around not able to keep itself buoyant, but still moving. At first we thought it was the arrow crab, but there’s no visible damage on the fish and its fins are in tact. It’s in a small quarantine tank for now but we’re really not sure what to do.

 

[Bugenar]

Update: It died. We think it was brain damage

 

[purpfish]

Had the same thing happen with my Midas blenny. (Rip Benny) I’m sorry for your loss sounds like there was nothing that could be done.