I purchased a YW Shrimpgoby from Biota last August. He's tiny, about an inch long. Since I put him in my 5' x 2' tank I've only seen him a handful of times. I was sure he had not survived as I hadn't seen him since November. The gravel got a major cleaning today and after lights out I saw him scampering about on the sand. He doesn't look like he's grown at all. Does this seem highly unusual?