Hi all.  My sons have decided that they LOVE the fish & aquariums, so they'd like one in their room.  They are really interested in the tropical fish, such as platies, danios & guppies.  We have a 30 gallon tank (& all the equipment for setup & cycling the tank before getting any fish). I was wondering if anyone could help me with how many fish of each kind, whether these are truly an ok mix & things like that.  I've done some research, but have gotten so many conflicting instructions about care & how much space they need that I hope someone on here can educate me.  All the information I've learned from here about my other babies has been EXCEPTIONAL!  Please help, I want to do this right so the fish will be as happy & healthy as possible!