Recommendations for fish in my fluval evo 52L

[Mr.Miyagiii]

I wanted to ask about suggestions about what other fish I could introduce in my fluval evo.
I currently have a Royal Gramma and a Redhead Goby. I also have a Sally Lightfoot crab which I'll be returning back to my LFS, as it is on a larger side, and after some research I found out that they have killed fish, I sort of don't want to take my chances.
I wanted a clown or two, but reading up that they can be quite aggressive, I don't think it would be a good idea to introduce them into my tank.
What other fish I could consider in a nano tank. Something that is colourful. I guess that's why I liked clowns,as they catch your eye when you look at the tank and they're not shy. And it was the reason I picked up Royal Gramma, as it looks beautiful.

 

[Sharkbait19]

A firefish should get along well and may be a bit more active than the gramma.
Alternatively, you can get one of the smaller shrimp gobies (stonogobiops species) and a Randall’s pistol shrimp.

 

[Nemo&Friends]

Another goby, a blenny , a talbot or springeri damsel, green chromis and dart fish.