I have a pretty, red betta named Sparky. He lives in a 3 gallon Marineland tank with 3 phase filter and a temp at a pretty constant 78 degrees. I've only had him about 6 weeks.
I treated him for fairly mild fin rot shortly after getting him. Two cycles of Maracyn/Maracyn2 combo. The treatment ended last week. His fins seem to be slowly filling back in and he continues to swim happily in his home.
Yesterday, though, he seemed not that visually alert. Perky, and hungry, but like he was distracted.
Tonight, he's blind. The only way he found his food pellets was by accident. He's swimming fine, he was definitely hungry because he gobbled up the pellets he managed to stumble into, and he seems otherwise okay, but he obviously cannot see.
There is no cloudiness to his eyes and he doesn't show any sign of popeye. He does have a white chin that has extended somewhat to his gill area. The white seems to be a pigment change, not a fuzzy fungus, and he has had this since shortly after I got him home. The Maracyn/Maracyn2 treatment had no affect on it. (I'm not worried about it unless you think I should be.)
Many thanks in advance for any advice on what might be causing the blindness and how to resolve it.