My brain is bursting with all of this--opinions abound, right? I've been keeping fish for nearly twenty years now, mainly fancy goldfish till about ten years ago. There is nothing remotely boring about a tetra tank. I guess now that Cardinals are being bred in captivity too, they may be as hardy as Neons--that was supposedly not the case before, so much so that I kept putting off the purchase for years. I couldn't stand it after multiple visits to the Amazon Rising section of The Shedd though. So far so good. My only tropical tank is a fifteen gallon, very established, stocked with overgrown live plants and Glowlights / Cardinals. Start slowly as you establish those plants though. I wouldn't add many fish at first, ever in a six gallon. I brought some of my fish with me from Detroit in a cooler three years ago--the sloshing soaked my ass in the U-Haul actually (battery-operated air stones).