you can find sites that will say you can have it in a 55 gal. look at live aquaria. they are probably the best and they recommend a 180gal. for a Piccaso. a lfs will tell you a hippo tag is fine in a 75 but that doesn't make it so. just trying to help you from having problems. yes those fish can be kept in a 75. will they be happy and healthy when they reach adult size? triggers can become extremely aggressive when they are in cramped tanks. I have a 120 gal. tank and I wouldn't dream of adding any trigger, large angel, or a tang. that said, it's your tank. best of luck.