I think my tank might be a little blah with just an oscar, is there a fish that would happily coexist and not take up much space? What about a full grown loach, im a little worried it might look to much like a worm though lol
In your 55g? No other fish. If you want to be fair to your oscar and make sure he gets to adult size, he should be the only thing in there. Believe me, you'll have plenty of fun keeping the nitrates low enough as it is. Let it be 'blah' and healthy for your own sake as well. The headache of constant water changes is heavier than the presence of another fish.