Beta Fish

Beta Fish are real fighters. I got one for Christmas and decided to print out a picture of another male and tape it to the side of the tank. The fish didn't stop attacking it until I removed the picture from the tank. I wonder if I can add other fish that aren't Betas to the tank without them being attacked? Anyway, I've heard that Beta's are easy to take care of and are tough. I see them at Walmart in small bowls and wonder how they survive in those little fish bowls. Doesn't seem like it would create enough oxygen to sustain the little critter. Oh, BTW, I named him "Shithead" lol.