We've had our betta since November. We keep him alone in a 1.5gal tank with a filter that we rarely ever turn on.
My boyfriend was trying to do the fish a favor and clean his water. Not sure how much water was changed. Used regular tap water and a drop or two of stresscoat. Didn't tell me about it until I noticed that the fish wasn't eating.
Once I found out, we switched him to distilled water (which he was perfectly happy in before) and took him out of the tank entirely. Moved to a sterile mason jar for the time being.
That was roughly two weeks ago - I've switched from pellets (which he used to love but now shuns) to bloodworms. Won't touch either. Has lost his little fish belly. Getting worried because now he won't even bother flaring.
Doesn't show any signs of ick or fungus, scales are perfectly smooth and fins are intact and beautiful. Have been reading for a few hours, but to no avail.
The only factor that has changed is the water type. Now that we've returned to the distilled water, only location has changed. Still no luck.