I have a double tail male betta that is 2 years old. We go him 2 summers ago and he grew quite a bit since we got him so he couldn't have been too old when we brought him home. He is in a 4 gallon tank with a filter and a heater set at 78-80F, ate normally and was a happy fishie. 2 weeks ago he stopped eating completely, lost his color and is laying around. Please see the side by side photo attached. Left is from last December and right is from today. I've checked the water's ammonia and all other levels with the 5 in 1 strip --all is normal and ideal. He can't go on much longer without food. I don't want to treat with random antibiotics and such if I don't know what the problem is. Does anyone see anything unusual in the photo? Please help. We love him.