Benefit of Fish in SPS tank?

[Footbag]

I keep reading that people suggest having at least one fish in an SPS tank. I'm assuming it helps break down foods to the point where SPS can digest them, which is balanced by the need to keep a low nutrient system.
Is my thinking on this correct? I'm planning a minimal number of fish for my tank, but want to ensure I reach and don't exceed the point in which they will be beneficial.
I'm planning a Goby/shrimp combo. I had been advised against clownish due to them potentially being aggressive towards corals. Need to come up with some other fish.
My tank has been cycled for a month and I have a few LPS frags in there, but want to get my system stable with the fish before adding any acros.

 

[thelittlereef]

I'll tag along with this. I wonder the same thing. Thank you for a good post.

 

[tibob32]

size of the tank would help for suggestions. That being said, a clownfish's territory is pretty small, so if yours becomes aggressive towards corals (mine became with my featherduster), you can just move the corals 6 inches and it'll be good. Many wrasses are reef safe. Foxface, tangs, bluethroat trigger...

 

[Footbag]

My tank is a 45g cube. So I am limited in my choices.

 

[megatsea]

I have only a yellow goby- he is small and loves to perch-on glass, rock, sand, not on corals so far....10 gallon
I have only one firefish in my 20 gallon....he swims looking for food, not interested in my corals-hides in sand...
Both are fun and easy to care for so far.