I just keep them because they are interesting and somewhat of a challenge to keep (it keeps me busy, at least). I'm really not too worried about fish dying. To be honest, with the exception of my TT eel, I would see the death one of my fish as more of a money loss than anything else, and most of my fish didn't even cost that much, so it's not that big of a deal to me. I just do the best I can to keep them alive and healthy, and if they die anyway, then it's not the end of the world. But so far, I haven't lost a single fish since I set up my 220 in July of '09 (with the exception of most of the danios I cycled it with).