I look after a Betta at my school who I've become quite attached to and he's just recently taken a turn for the worse and is on the brink of death. First off, he's had fin rot for almost 2 months now and I've been trying to treat him with Melafix for 2 weeks and it was working until yesterday. He's in a small one gallon tank I believe and it has a filter but no heater. He's usually weak and lays on the bottom but would swim around every now and then, but the past two days he's not been moving and looks dead even though he's breathing. I don't know what to do, but I don't want to give up on him.