I'd try to move the cats, they'll get big and will want brackish water. Otherwise I'd probably keep the others, though the JD might beat up on that O, and if not he may well get too big for the tank with the other fish. Oh and you'd be surprised how long those danios will last, I've kept them with big oscars and they rarely got eaten.
Looks like lots of hiding spots...good thing, if he had no place to hide that crayfish would be toast.
