I have had a green terror for 3 years. Never any issues. He used to be very active and feed aggressively. However, over the last two weeks he has stayed in one corner of the 150 gallon tank and seems uninterested in food. His poop looks white and stringy which isn't normal. 3 weeks ago he had fin rot on the end of his tail fin which was treated with Pimafix and Melafix and it's 90% recovered now. I've soaked pellets in garlic and he's still uninterested. I have also noticed his coloration isn't as good. He's showing pale vertical stripes from his head to midsection. In two occasions I've seen him swim face down in a corner and appear to not move or breathe. This happens for about a minute. All other fish in the tank are fine. Water is fine. Aquarium Salt was added to the tank to help with the rot but won't be adding any more. Any ideas? Thanks in advance!