Just thought I would comment (I'm brand new to RS)....but I also own a blue hippo. I bought him very small, probably a little over an inch. But when he was first introduced he was very intimidated and played dead often. Also, being he was so thin he would be able to wedge himself in between rocks and just remain there for a while. But after about a week he became less timid and always started to swim without much fear anymore. He also eats anything and everything i throw into my tank, and is now fat and about three inches. My advice, just hang in there and he will come around. Cuz i completely understand your reason for concern, and they are beautiful fish!