EMERGENCY!!!!: I purchased a betta 4-5 days ago and he was put in a heated and filtered 2.5 gallon tank. I noticed he had fin rot shortly after purchasing him but he was eating just fine. This morning I woke up to him with white fuzz covering him (I’m guessing fungi) and most of the color gone from the scales. The fungus was not there yesterday. His head was above water and he was balanced on a leaf. 12 hours later he is barely moving whatsoever. I have added API Bettafix hoping to aid in helping the situation and unplugged the heater. I’m afraid he will die tonight. I don’t understand how this happened overnight...