My LFS told me this is the season for lots of Betta diseases...one of mine just got Ich, the other is doing fine. I have the sick one in a 4 gallon in 85 degree water...Bettas like warmer temps...try increasing the temp 1-2 degrees a day (don't shock him). I've also been giving him salt baths (non-iodized table--yes, I researched this so I'm not crazy) plus added 1 tsp. table salt per gallon to the tank. Water changes obviously go without saying. Needless to say, this is the healthiest he's looked (aside from the Ich--which is now going away) & he's actually made his first set of bubbles for a nest.
Basically, clean the water, try increasing the temp, and maybe add a little salt (caution on that last part). Usually, new water just gets them back into it. Otherwise, observe him for a few more days & really look for signs of sickness.
Basically, clean the water, try increasing the temp, and maybe add a little salt (caution on that last part). Usually, new water just gets them back into it. Otherwise, observe him for a few more days & really look for signs of sickness.