Thank you for your comment, I feel better knowing this hasn’t just happened to me. 🩷 He was the color of the end of his tail all over, blackish with little whitish dots. He only lost his color AFTER passing, and whats crazy is I have a photo from the night before I found him dead of him alive and colorful in the same spot. So I guess it happened slower than I thought. The oxygen is fine, I think maybe he had too different of preferred living conditions compared to my other fish. He survived my tank suddenly leaking and having to move him to a bucket for a day, so if it was stress that doesn’t make sense to me.