Questions about stocking a standard (not long) 20g

[biomekanic]

I'm going to be setting up a 20g tank in the near futures. For corals, I'm going with 'pest' species; xenia, GSP, and blue encrusting clove polyps.

I'm planning to have mollies in the display as algae control, and a schooling fish.

Any recommendations for other fish that would fit a tank that size?

 

[LetItReef]

(Chrysiptera springeri) I currently have this and not mean at all.
Bangaii Cardinal
Yellow Assessor
Designer Clownfish
Two-spot Blenny