I just finished cycling my 20 gallon long (yay!), so I added 6 glolight tetras that I already had. I was thinking about this stocking:
6 cories (juli or panda, not sure)
A couple red cherry shrimp, or a mystery snail
The tank is going to be moderately planted. Thanks.
You could certainly add more cories. They would really appreciate it. It looks like a great stocking level. The red cherry shrimp will reproduce so you don't need more than a couple of handfuls to start out with.
Thing about the betta and shrimp, if the tank isn't heavily planted enough, the betta will hunt down and eat the shrimp. I raise RCS and add the culls to my betta tanks for a bit of extra algae cleaning, but more than often I see the bettas hunting down the shrimp. It's really one of those things that is one or the other.