I have 2 clowns, 2 hawks , 1 small yellow tail demsel and 1 big domino demsel in a 34g ResSea Max, for now alomost 6 months...they have all been very good..i always used to read that Demsels fight alot...but mine didnt....BUT to my horror today just as I woke up I saw that the black Domino Demsel was running after my Yellow tail demsel and my God...the poor little fish is all like scratched up n all....I didnt know what to do so rt away i fished out the yellow tail for now and have him in a bucket ...the Black Domino is sooo damn fast I can't get a hold of him...Iam so upset... any one who had an experience like this and if someone can tell me how to take care of the Yellow tail demsel would be soooooooooooooo appriciated:):helm2: