My yellow tang is nibbling on my newly purchased lawnmower blenny and is swating at my porcupine puffer. He has been in the tank the longest almost 3 months. The puffer has been very dormint in my tank where at the LFS he was very active. He also frequently puffs up which looks cool but I know is stressing him out. The problem that I am facing is that my Girlfriend is in love with this fish and is brought to tears when I told her I might need to take it back. This fish used to be very docile and shy when it was first put into the tank but has become very territorial and aggressive as time goes by. I would like to "reset" this fish to how it was when it was first introduced to the tank and any suggestions would be great. Info about the tank: 50G w/ 15G sump and 10G Refugium. DIY Protien skimmer, 2x 55w PC lighting, 100lbs of LR, 40lbs LS, UV sterilizer (5W), mag 7 return pump and rio (200gph PH). for current. coil denitrator. am=0 nitrites=0 nitrates=0 weekly 7% water change with RO/DI Water Inhabitants(in order of entry): Snails, Hermit Crabs, Yellow Tang, Porcupine Puffer, 1 bulb anemone, Pair True Percula, Lawnmower blenny.