its a butis butis. An awesome fish, often refered to as crazy gobie or dragon gobie since they often swim upside down. They are predatory but get along with similar sized community fish without issues. I had one for awhile, he took guppies and bloodworms with gusto. Won't touch pellets or flake. They can handle fresh water but really appreciate some aquarium salt in the tank. The have limited color change abilities to blend in with their surroundings. Congrats on a unusual and good find, I'm still trying to get another one for my tank.