don't know much about them but if you can feed them i would say give them some mysis and garlic. i had some candy canes that were receding and i gave them mysis everyday for about 1 week and they came back at full strength. i think the problem was when i got them they stressed and expelled the photosynthetic algae they have in their cells and were slowly starving so when i fed them it gave it nutrition to keep it alive and also helped them regenerate their lost algae cells that were expelled.

worth a shot! good luck!