a group of pink tailed chalceus would look cool in a 210, i've got 3 of them growing out in a 55gal. i love the way they stay in the top third of the tank
I have spotted silver dollars (not sure on the specific species anymore, theyre nice though, the ones that get the purple body). Theyre going to get too big for the tank and there seems like 10 isnt enough of them, they constantly fight.
Why do you think silver dollars will out grow a 210 galon tank? They usually only max out around 6 inches or so unless it is the wide barred blue hooks.