Fish recommendation for 20g with existing clownfish pair?

[NanoReef303]

I have a 20g LPS/Softy mixed reef tank that is currently inhabited by a pair of Orange Storm clowns and 2 skunk cleaner shrimp. The clowns were juveniles when I added them about 7 months ago and seem to inhabit the top of the tank most of the time as they seem to want to stay away from the shrimp who each inhabit a different rock structure (2 islands aquascape). I want to add another fish so I’m starting my research now. Looking for a reef safe captive bred fish with some good color if possible. I was thinking of a fish that will primarily inhabit the rock work or sand since the clowns are up in the water column, hoping that would mitigate any aggression from the clowns. Any recommendations that I should look at? So far the biota court jester / rainford goby seems like a good possibility. My primary worry is aggression by the clowns.

 

[Cell]

Goby or blenny. I doubt the clowns mess with them.

 

[NanoReef303]

Goby or blenny. I doubt the clowns mess with them.

Thanks. That was the route I was thinking of going. Any specific recommendations? The rainford / court jester goby looks like it has nice coloration.