i have been reading (multiple sources) including here on RC which is where i found these fish described first...there are 2 "schooling bannerfish" of the genus H. 1 good one bad...u want the diphreutes...... and not the H acuminatus which have been documented as terrorists....authors scott michael,and bob fenner both agree that a tank of 75 is appropriate for a bannerfish...but what is unclear as always is if more than one can be kept in that size cage...i would like to have 3 in my 90... but i think i will do 2 since i will have a scopas tang, 3anthias(fathead) and maybe 11 or so chromis...i want a peaceful setting and healthy fish...i hope my plans aren't crushed ... good luck the way to tell the difference b/t the good and bad is as follows..."dphruetes(good fish) has a more rounded breast, less protruding snout, and the middle black ban ends @ the corner of the anal fin" they are available through vivid aquariums.com,,,,,,,although i have never bought from there if you do buy from them let me know how it works out ...vividaquqriums is in la...don't know u'r proximity to there