I have a Yellow Watchman Goby/Tiger Pistol Shrimp combo in my 220g tank. When I added them about a week ago, they paired up instantly and made a home in the sand. Today I came down to find some of the holes closed up, and the YWG swimming around at the top of the tank, sometimes resting on the rocks. I caught a glimpse of the shrimp today, so I know he's still around. What's the deal? Is the goby lost? Hungry maybe? Will he go back to his buddy?