Fishing, sorry couldn't resist. From what I've read though it could be anything from septicemia to dyes in the food you are feeding it if you are talking about a pet fish.
no
Yes, it does.
Non -vegan polishes can contain fish scales ( red and pink tones) or oil. So it depends on the polish.
Yes some red lipsticks can!
Salmon meat is red. Also, the largest freshwater fish, the Arapaima, also known as the Paiche has red tinged scales. It's found in the Amazon.
No, heart scales can't make a red gyarados
A dangerous acid
acids
Beet juice.
Acid
The sunset makes the sky turn red.
The sunset makes the sky turn red.