:iagree:
The 40g is too small for the fish you mentioned, especially those silver dollars. Also, silver dollars are little piscine lawnmowers: they'll eat most every plant you put in that tank.
I'll be putting up a tank of similar size, soon. I'd suggest looking at gouramis, rasboras, and small loaches. Or, from South America, a school or two of tetras, plus a pair of apistos and some cories would be neat. :idea: