I finally got nine beautiful Silver Dollars. They are juveniles, probably 1 to 1.5" only. What would be, in your experience, the "safe size" for them to be introduced in the Oscars' tank so they don't become a snack for the Oscars? I am raising them in another tank, with peaceful Rainbowfish.

Pepe
Santo Domingo

How big are the oscars?

i think as long as the sd's cant fit into the oscars mouth you will ok. im not sure on how fast sd grow but eventually they will be big enough.

My 2 Tiger Oscars are 8 and 9" long. My 9 Silver Dollars are juveniles 1 to 1.5".

As for present time, if I put them there they will be gone in no time.

Pepe
Santo Domingo

With 8 or 9" O's I would wait till the sd's are around 2.5 to 3"

I would try 3". But please dont take my word as gospel as anything could happen. I have just put 4" clown loach with 10" oscars and all is well. They got chased for a day or two but had no harm done.

The problem with silver dollars and oscars is that silver dollars are thin. So the usual rules of them not fitting in you oscars mouth is not so staight forward as with most fish. They may not fit in your oscars mouth but your oscar may still have a go at trying to eat them (and injure or kill them). Silver dollars are fast fish but its best not to put them in with oscars until the oscar wont see them as a possible meal. To be on the safe side I would grow them until their height is twice the size of your oscars mouth