MyGoldfish wrote:My koi fish was perfectly fine this past week and yesterday morning, but when I got back from highschool, she was at the bottom of the tank, laying on her side, and she could only breathe. She couldn't move any other part of her body, it was as if she was paralyzed. I covered the tank with a towel so I couldn't see her suffer. I looked into the tank this morning and she had passed away. I have no idea what happened, she was perfectly fine and I had her for almost one year. What could have happened to her?
How big was the tank, did you have a filter, how often did you change the water?
Koi are huge fish that really need to live in a pond. Unless your tank is huge she likely died from something related to poor water quality :c