I am in urgent need of help. I just returned home from vacation to find that my heater in my 2 gallon betta tank malfunctioned and put the tank at 90+ degrees. I have unplugged and removed the heater and done a 20% water change with room temp water. My betta, Charles, appears to be as active as usual but the ends of his fins look like they have been burned. Is there anything I can do to help him?