Another thing I would definitely consider is the MAX size a fish can get. For example, my wife wanted a desardjini sailfin...Adult size is about 1.5'....Now, I could put it in my 8' tank for a while but...At 1.5', It would need a BIG tank. My 4-5" tangs look cramped. I can't realistically say I will ever get a tank big enough to house a fish the size of a cat or small dog. If I had one and had to give it away, who would I give it to that could house it? Remember by the time it is grown, you will love it, but may not be able to afford to keep it. Don't condemn a fish to misery from lack of planning.
I'm not saying you would do that, just a reminder.
