Ours is in a 75g and has killed a yellow assessor and royal gramma. The rest of our tank mates dont take any crap from it so it leaves them alone but if anything shows weakness, it will get pestered and harassed to no end. They are however, awesome to watch and they're always busy (and beautiful). Other semi-aggressive fish should fair well but if you have smaller community fish, be prepared for death (doesnt mean it will happen, just that it can). The only small fish left in there are our Randall's goby and tailspot blenny and for whatever reason, they dont back down to the wrasse so he doesnt harass them.