Hoodie

Thanks for the detailed response, that is what I was afraid of when researching but wanted to confirm.

Ph 8.0 Ammonia Nitrite and Nitrates all 0 One of my Neon Tetras has developed a gash/lump around its mouth, and generally looks a little off. It is not fuzzy but I have it separated in a quarantine tank for now. Have not found anything matching the description based on research so hoping someone can help me.

Water parameters are: ph 8.0 ammonia nitrites and nitrates are all 0 (nitrates fluctuate between water changes)

1 year in the hobby and this is my first sick fish. One of my ember tetras is looking worse for wear, it is smaller and is Turning black and discoloring. I cannot find much information online about what causes this, can anyone help me diagnose what disease it might have? His eyes are a bit popped out so I was thinking Popeye but that would not explain the coloration.