fighting fish

I had one male beta fish in office. my maya bought for me, I called"PAPA" lol... I've had my fighting fish for about 1 years and a half now i take care of it i clean its tank probably once or twice a month feed it daily but i don't know how long it has to live. Recently, papa is sick, he's apparently has a fungal infection, I am not entirely sure what to do. I went to the Pet store and got a Fungal treatment, so hopefully he'll be k. god grace he's fine now and look healthy after few weeks....