Great fish to have.
You can pick them up for next to nothing costwise....and you get a fast-growing lotta-fish for your money.
They look a little duff when small.....but when big are simply awesome.
As said by the previous poster....these are skittish (so maybe have a 2-net system for catching them).
feeding is no problem.....feed a good balance to include spirulina flake.
Good clean tank, good aeration, good filtration and good water changes.
As for partners in the tank.....many fish will work well with silver dollars. I would avoid delicate slow moving small fish such a chocolate gouramis as they may be in the way when a silver decides to dart.!!
Very small bite-size fish may easily be mistaken for food.
If you are tempted by silver dollars then next step up are the even more awesome red hook pacus (Myloplus rubrippinis).