So my third Betta fish over the years passed today. I'm wondering what happened. Basically the entire story is I had my first fish who lasted many years. He was awesome but then my next fish did not make it very long so I made it a point to take really good care of my new fish. I didnt get him very long ago. Maybe a month or two. This winter has been very cold so for Christmas I decided to get his tank a heater along with a few accesories that I thought my betta would like. About a day and a half ago I cleaned the tank, put in new accesories, and put the heater in. He was fine and active at first but then he began to not get very active. Then he started to not eat his food. I read that he might be stressed so it might give him some time to get used to the temperatute change. Then today my fish was just floating towards the top. He had passed I want to avoid this when I get a new fish. Can anyone tell me what happened?? The heater was also one that only stays on 78 degrees so I didnt think it was too hot.