I'm seriously worried that Jeffrey needs a playmate. I have a 5 gal. plastic tank, light hood, real plants, filter, bubbler, and soon to be adding a heater. Can I add somethnig other than a snail to the tank? Zebra dannio? Neon tetra? I know they like to be in a school. Would there be room in a 5 gal for 3 tetras and my betta?