New Fish, possible tankmate?

[BettaCavy]

Hey guys
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.

Gracias!

[LeroyTheBetta]

Looks like a comet goldfish to me. Théy'll get up to 10 inches, are cold water fish, and will nibble your betta's fins to bits. NOT AT ALL suitable to be with your betta, and if you're worried about space in your dorm room, rehome him or give him to a fish shop in your area.... Kind of like the quote from the movie "Jaws".... "We're gonna need a bigger boat". Except, you're gonna need a huge tank for that comet.

[BettaCavy]

Yeah, I was thinking that it was some sort of goldfish but it's very small (about half the size of my betta) and the fins don't exactly match up with some of the pictures I found online, so I wanted to double check. That combined with the fact that my betta is extremely aggressive...I ended up getting a cheap 5gal tank for my baby brother and giving him the fish, so he's pretty pleased about that. My guess is that we'll have to upgrade once the fish grows (and then I can steal the 5gal for my betta, buahaha) but for now it seems to be pretty good. Thanks! ^^

[LeroyTheBetta]

Sounds like a good plan, and I'm sure your betta would thank you if he could. :)

[turtle10]

Your plan to buy a new tank once it grows won't work. Goldfish won't grow if they are in too small a tank. Well, actually their organs will grow but not the outside of their body. This is a very painful death for goldfish. I would either plan to get at least a 75 gallon tank. To give you a good idea of the space they need, comets do best in a pond.

[alixhero]

i think the betta will attack em more then the gold fish nimmble .....