Dead Betta... body is black

[Citrusy]

I had a white betta fish named angel and I have been away for the week. I left Monday October 1st and gave her one of the 7 day betta feeders. I just got back home today and found her dead. She was completely fine before i left. She was in a 10 gallon tank by herself with a filter and heater. I had just done a 30% water change the day before i left. When i got home I found her like she is in the picture. I have no idea what happened. I don't even know what disease that is and I have read quite a bit about their disease's and saw nothing about this happening. She is already gone but I just want to know what happened and if I ever get another betta what the symptoms are and what to do to prevent this.

[MyRainbowBettaFish]

I am sorry about your betta. The 7 day feeders can release many unneeded chemicals into the tank, and bettas can eat themselves to death.

[NyaNyanNaa]

^ As MyRainbowBettaFish said, that's a possible factor.

It's also possible that it was parasites that got a hold of her while you were away.