Royal Gramma and Sexy Shrimp!

[mikeclarke]

I have a royal gramma in my 20gal FOWLR tank. I have two clowns, two blue damsels, a coral banded shrimp and some snails and hermit crabs. I think that the shrimp really rules the roost.

Things were going well until a couple of days ago, I've noticed that the royal gramma sits in the corner at the top of the tank vertically. I did a 20% water change and tested everything to be okay. The pH might be a tiny bit low but I don't have a LFS. Does anyone have any ideas/suggestions?

On a side note, I had a tag along crab that I never really got a good look at from some live rock I bought. I put some shells in the tank when I bought my other crabs and there were big bits of a big crab in the morning. I think that the crab came out of his hiding spot and tried to get into one of the big shells but didn't make it before the shrimp got him.