Per WorldCichlids.com, bottom feeders like pictus catfish and clown loache are compatible with oscars because they stay on the bottom of a tank whereas oscars stay in the middle and top of the tank due to their larger size.
Oscar Fish enjoy living in pairs or small groups. We would recommend keeping at least 2, or even 5 if you have the space. Keeping three isn’t always a good idea as two of the fish could bond and dismiss the other one.
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