I decided I wanted a small school instead of a solitary betta fish. I added two black neon and two glow light tetras that will school together and each will be two inches full grown. This breaks the rule of one gallon in the tank for every inch of fish, but I'm careful to change 10% of the water every week as suggested and I also test the water's pH, hardness, chlorine, nitrate, nitrite, and ammonia levels at the same time. This appeals to the nerd in me-I had to look up what levels were normal for my tank and had flashbacks to biology class.
A black neon tetra admiring its reflection.
The glow light tetras are more aloof than the black neons.
It's very peaceful to watch the little tank contained ecosystem doing its thing.