Time for CUC?

[Demoe]

Added fish a week ago. Parameters are good. Fish doing good. Rock is starting to get brown on it. Is it time for a CUC? If so what should I get? Attached a pic for reference.

 

[Mr. Mojo Rising]

not all cuc are the same.
I would suggest to add omnivore critters to the tank once you add fish, to eat up any leftover food.
Herbivore critters should be added once you see algae.