when to add cleaner fish and others?

[cmbarnes10]

I have a 20 gallon tank that has only had the fish in it about three weeks. I have two false perculas, purple pseudochromis and a blue damsel. I also have 10 blue legged hermit crabs and one mexican turbo snail. How soon until I can add a cleaner shrimp? How soon for a starfish?

 

[cmbarnes10]

oh and how soon can I add an emerald crab???

 

[ophiura]

Very few seastars will be suitable for this tank.
We'll need to know a lot more about your specific water parameters, etc.