Neon Tetras: my betta's tank mate. You take a risk putting other fish in with the betta but I read up on good tank mates and they mentioned Neon Tetras. They are a schooling fish so it's good to get more than one. (i got two from the store but one had died within hours, he must of been sick..on my next days off I have to grab three more, it's a ten gallon tank, it shouldn't stress out the tank). 1 square inch of fish per gallon is a good rule of thumb.