Originally Posted by LebronTheBetta
A snail or shrimp is the only one you can put in a 5 gallon. No frogs, you need a 10 gallon for that with the Betta. A nerite snail or a few shrimp are the only ones you can put in. Remember, Bettas don't get lonely. Nor do they want "friends".
If you want to add some tankmates, you would have a 10 gallon tank and a good filtration to keep up with bio loads.
It depends on your betta's personality. If he decided to eat the shrimp or the snail or kill the fish. It'd be best if he has all the space to himself.
Add some live plants if you want to "make it more interesting" tank.