Are goldfish social animals?

I have a male goldfish and I was wondering if he would be happier if i added another fish to his tank? I don't know if fish are social creatures that would benefit from company or not. Also if i were to do this would i have to get a larger tank than 10gal to support 2 fish?
Update: my only problem is that at my dorms i cannot have any larger than a 10gal.
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