I just had to remove my new 1" percula, because my 3.5" Yellow Tang was trying to eat it. I also feed my tank live food quite often, though. Young FW minnows and small FW shrimp. This may have conditioned my Yellow Tang to look at smaller fish as a meal. I honestly don't know. A 7" Hippo would have no problem ripping a 1" clown to pieces. If you do mix them, you should probably keep a close eye on them for a while.