Where did you get that damsel from? If you got it from your LFS, take it back. If you collected it from the sea, I suggest you keep him in your sump. Releasing captive aquarium fish back into natural waters is not allowed according to the Biodiversity Act as well as the Act governing the import of both marine and freshwater fish. Releasing aquarium fish into local waters is one of the reasons that the import of aquarium fish has been questioned by authorities and this type of activity if found to be the practice might result in importation being limited or worse stopped.