Delila and Sebastian

It has been a very sad last 48 hours for me. Over the weekend, I noticed my Delila’s right eye was bulging out and her scales were all dark. I thought of Shaker and how he had an infection like thing. I cleaned out the tank and separated them into two buckets. Delila being the sick one had her own and Sebastian and Coco shared the other. While cleaning, I broke the heater so the water was too cold for them to be back in the tank next morning. I went to Walmart early in the morning and set up the new heater. I went home for lunch and realized that it wasn’t plugged in. Irregardless, I saw Sebastian floating on the top while I was home cleaning and waiting for the water because I was going to dump them in within the hour of heating. I thought it was weird that Sebastian was fine, but died while I was home. So I just dump Delila in by herself because I figure she is sick and she can get use to the water by herself. By the time I got home, her eye was much better so I figure it is because I treated the water and she is healing. I dump Coco back in and left them alone. This morning I work up, and Coco was sucking on Delila and she is all white. Now I understood why Sebastian died – Coco was the culprit all along, that was why the other two had scars and Coco didn’t have any. I didn’t see the signs because he was always good when I am around. Every time I checked on him, he was sucking the glass and being good. Now I lost two fish and I don’t want him anymore, but I don’t want to kill him.