You're very lucky you have a nice betta fish....when I tried keeping my betta fish Cyan with 6 neons in a 40g....that did NOT work out. My betta ended up killing half of them....I guess he just didn't like the company. I saw him chasing them around at first, but I figured he'd never catch them since neons are pretty fast. A couple days later I find three neons dead, one with a hole in its body and no insides. Yuck! I was feeding my betta plenty, though, so hunger couldn't have been the cause. Cyan got along well with my African Dwarf frogs perfectly well, though...(don't worry, I took Cyan out of the tank after he killed the neons)