what other fish can i put with my 8" peaceful oscar and my 5" pleco?

I have always had oscars and cichlids together. Just get cichlids that are as big as the oscar. Also Jack Dempseys, and yes silver dollars.

is a 90 gallon tank(48"L x 18"W x 24"H), i know it has to be a big peaceful fish, because the oscar may eat it if it is smaller. and i DON'T like the sharks, and the tinfoil barb. btw i CAN'T put another cichlid with him because last time he kept getting harrassed by my small cichlid. so NO more cichlids. i heard silver dollars CAN live with my oscar, but they will DIE, because my oscar is a messy fish and the silver dollars are 6-pack schooling fish that WILL get WAY TOO big(8") for my aquarium(and they are not that hardy as well)

Try this link for ideas )

http://www.oscarfishlover.com/index.php/Tankmates/Oscar-Fish-tankmates.html