My gallon has 1 female betta, and 1 snail. So far no plants, but going to be adding some as well as some large rocks. Can I put in more fish, and which kind? Some of the sites I'm looking at give conflicting info on what to add with bettas. If I can I would like to add either a school of cardinal tetras or some guppies. Like I said some sites said it was ok to add these, so said no way. Is my tank big enough to add either one of these?