I know that there are a lot of people here that will disagree with this but here i go. If you start the tank with live sand and you have the right salinity and temperature i would recommend launching some space monkeys. As we didn't send a human into space first you wouldn't send a $20 fish into a new tank first. I have started all of my tanks with damsel fish. they are tough as nails and cheap. they start the nitrate cycle, scratch the itch to buy a fish, and some of them tend to live; the downside being that you can be stuck with damsels. If you don't already own it, go out and buy The conscientious marine aquarist by robert m. fenner. Welcome.