well if need an opinion on the tangs... I have one
it is very tough adding a mix of tangs, but I have done it.. I have a powder blue, purple, yellow, and blue hippo all living together... Its not a happy family - the yellow gets picked on from the purple and PB... But my blue hippo just gets around the tank fine... But if u can rearrange some rock for their territories to get renewed in your tank.. also if you put the hippo in the tank in the dark it will help a lot... this is what i have been doing for adding fish to my largely populated tank... good luck lynn..