yip, you often see baby Oscars in 10g tanks in the pet store bearing in mind not many fish stay there for very long. Mine are in a 300g tank and even that doesn't seem like enough space for them cos they get up to such mischief! they enjoy lots of space - nothing smaller than a 55g for one and 125g for two - they messy fish and need a lot of maintenance. So if you're getting a big tank keeping you baby in 10g will be fine while your new tank cycles but anylonger than that could be fatal for your little fishy.
Well, Good luck!
Kerry