I got a new betta a few days ago for my boyfriend, but he doesn't have a tank to keep it in so he lives at my house until he can get one. He shares a tank with my old betta, who is very happy and healthy in this tank and doesn't mind sharing (separated, of course), but the new one just kinda hangs around at the bottom of the tank. He swims occasionally, but he doesn't eat and likes to wedge himself in small places. My friend told me that living with another fish could possibly be stressing him out, so I put my old one in a different tank and let the new one get used to it for awhile. He swam around for a little bit but now he sits at the bottom again. Is there something wrong, or is he just weird? I've never had a betta fish act like this before.