I'm in the middle of one of those "what-kind-of-fish-should-I-add-to-my-tank" nightmares that make the hobby worthwhile. I will have a clown knife and a silver aro in my 220 for sure. I am considering some catfish, but I've recently become intrigued by the idea of a small school of silver dollars. I'm not familiar with them, but I think I would like the red hook variety best. Any thoughts or PICS? Which types/species have more red in the fins as adults? Are any considerably more demanding than others? Any help or pics will be much appreciated.