At the end of school, about a week ago, my friend gave me his betta fish (he could not take him home with him). He had been in a .5 gallon tank, and I could tell that it was not cleaned very frequently...I bought a small Kritter Keeper (9"L x 6"W x 8"H, not sure of size in gallons) for him, and put him in water that stays at about 75*F. I've been doing 50% water changes every 2 days.
I just noticed that he has dark edges on his fins, and I'm worried that he is developing fin rot...can anybody tell me if I'm right (or if I'm just paranoid)? If he does have fin rot, what do I use to treat it?
Sorry the picture is a little blurry...I tried to get the clearest one I could. :/