i wanted to know if i can keep two or even three types of chromis in my 60 gallon tank. i have a lot of hiding places and space for them to swim. Right now i have 3 blue/green chromic and would like to add black bar chromis but I don't know if they are aggressive and then i want to add some blue reef chromis. Are back and white chromis peaceful because i had read they more of a damsel than a chromis? Thanks for all the help guys.