Tang cleaning a Tang

[reeftank250]

I have a large Sailfin tang which I observed being cleaned by my small White Freckled Tang (Acanthurus maculiceps) as a cleaner goby would. It was very weird. The Sailfin had its fins all extended out and his color had changed when the Maculiceps was picking at it's sides. Has anyone ever heard of this before?

 

[shovel]

have seen my hectors goby do that to a fih days later it was dead!