I have a red spiney reef safe starfish and it appears to have a injured arm. It seems as if it is hollwed out with no feelers except at the end. It just hangs in the water unlike the rest of the arms which are showing no signs of problems. The shrimp have started to pull at the infected arm. Since starfish can regrow arms I was thinking that I can take a sharp blade and remove the infected arm and hope for the best.