mine took right to all of my fish....I have 5 cleaners and 3 fire shrimp in my 125...I have seen them cleaning gills, fins, and my flagfin angel even likes to have his "teeth brushed"...he will open wide and the shrimp will clean the inside of his mouth. I have 2 separate groups, there are 3 that stay on one side of the tank and 3 that stay on the other side (the other 2 are "wanderers").