I have had this Coral Beauty for almost three months now (in a 5 month old tank) and over the last 5 days or so i have been noticing his back three fins are looking pretty torn up. He is by far the biggest fish in the tank (a 29 gal bio cube) and i have never seen any other fish act aggressive toward him so I don’t believe he is being nipped at. I have two clown fish a six line, two cleaner shrimp and urchin. Ammonia 0 Nitrate 0 Nitrite 0 PH 8.1 - 8.2 Up until now his top/bottom/back fins have always looked very 'crisp' with a different shade of blue for an outline. His yellow side fins still look great, no signs of 'decay' I don’t dose anything and maintain a regular 10 % water change each week. The last piece of live stock added was a cleaner shrimp approx 1 month ago. All other fish/coral appear fine. The coral beauty’s behaviour seems somewhat normal, he is eating frozen and flake, however has been hiding a little more than usual over the last three days.