What would you add to my tank?

[resuahknaf]

I currently have a 40 gallon breeder, with a pair of clowns, 1 pajama cardinal, 1 watchman goby, 1 blue knuckle hermit crab, 1 tiny red leg hermit crab, 1 urchin, 5 snails, and 1 camel shrimp. All of the fish are adolescent, definitely not full grown.

What would you add to the group? Can I add more pajamas or will the one already in the tank try to fight? I have read so much conflicting information.

 

[1112-425XL]

Tailspot blenny or Lawnmower blenny, either will add a lot of character!

 

[Stang67]

Springerii damsel

 

[jabberwock]

Pistol shrimp