I've got a betta in a 1 gallon with a filter and heater set up. He's been fine and recently I've noticed he's been a little blue around the gills literally...and laying on his side at the surface of the water. Also, he used to swim all around the tank and now he only swims at the surface. Any idea what's wrong?
He used to have fin rot, but I saved him from my sister, and he's doing better, but still recovering...I wonder if that could have anything to do with it.
Please let me know if you have any advice, thanks.