So last night my friend's roommate came in with a fish in a bag and gave it to me, because she knows I have a fish and she doesn't have any fish stuff. So I stuck him in some fresh water in the little half-gallon my first Betta came in (he's now happy in a 2gal with regular water changes). And now I have some sort of fish. (http://i51.tinypic.com/2n8oncz.jpg
The question here is twofold: (1) what kind of fish is this, and (2) can I keep him with my Betta, or should I keep him in his own tank? Either way I know I'll have to get another tank, but if at all possible I'd like to keep the new fish with my current fish, just in terms of size with my dorm room.