I have a 35g tank with 2 small clowns 1 small blue hippo tang, 1 small yellow watchman goby, and 1 diamond goby. I had a small yellow mimic tang that died and I’m wanting to replace him with another fish. What should I get? I also may get a pistol shrimp to pair with the gobies, will that be a problem? Below is a picture of my rock (I don’t have much)