I am writing about my room mate's betta, one year old. He is sick, see pic below. I have never personally owned a fish, I am learning about it now.
Background: fish lived in a 1 gallon tank with aerator for a year. He started looking sick, whitish patch on his side, spitting food out, lethargic, hanging out in a corner.
We put him in a bowl with 1/2 gallon fresh water (distilled, that is what she had been using), put the aerator in it and he perked up a tad and started eating again.
A few days later, she got a 1.5 gallon tank with aerator and filter, and some tap water treatment. She also got Lifeguard all-in-one treatment. The treatment called for one pill per 5 gallons of water so she estimated how much for the 1/2 gallon bowl.
Treated him for a few days then moved him to the new 1.5 gal tank. She treated for a couple more days. The treatment instructions were not followed exactly. They called for removing the carbon from the filter during treatment, didn't do that. But he did have a few days of treatment in the bowl with no filter running. I am assuming the filter traps the meds, but don't really know. And, a 1/4 water change at day 6, didn't do that step.
It's been about a week since treatment ended. He is better but still not right. He likes to stay by the filter, keeping the patchy side of his body up against it, maybe it itches or hurts him there? He doesn't seem to swim quite right, either, but there is now a big castle in the tank with not a whole lot of room to swim, so hard to judge. He likes being in the castle too.
The question is, is this a fungus or something?
Thank you in advance.