take necro's setup as an example of how RTCs can be kept with much larger oscars in terms of AT LEAST equal length but much larger body height. yet even necro sed that it wont be possible in a few months to a year cause the RTC will outgrow everything!
i've done it before... 3+ft RTC and really fat oscars... what was odd was my Oscars all came in after i got my rtc...
until my rtc smashed my tank... dumb me then.. i was less than 14 then i think... hehehe.
BUT RIGHT NOW.... ABSOLUTELY NOT. hahaha. and heres the catch, not only that the oscars will get eaten... the RTC will eventually outgrow the tank (unless of course if it's REALLY REALLY huge) and so you'll eventually have to transfer him to a pond.. and if you still insist on putting the oscars in a pond, they won't be just as nice. their markings will have less meaning oscars are more of tank fishes and rtcs are more of a pond fish....=/