Hi! I'm a relatively new Betta fish owner, I got mine in September. His name is Dobis and he is a very beautiful light blue crown Betta. I recently moved him into a larger bowl (1.5 gal, he used to be in a 1 gal). Also I got him a water heater, I figured he needed it because-- being a tropical fish-- he is not equipped for Vermont weather!
Recently I've noticed his (very light blue) head turns splotchy black and his eyes turn very dark. And his gils (not sure if that's what they actually are, just a guess) turn black and fan out around his face. I'm really worried about him! Does anyone know what it is? Or how I can help him? Thank you so much :)