My Betta fish, Bubbles, died today, March 15th. I went out to the fish store and bought him some Betta Medication. I followed the directions to put 18 drops of this medication in the water. Yesterday, I had noticed the ends of his fins we turning red and 'rotting off'. His belly also was turning yellow. I have had him for as little as two weeks. I had only changed his water twice, and fed him twice every day, but not too much each time. What did I do wrong? Someone, please help. I am really sad. :(