When I compared Velvet and Neon, I noticed Velvet has a small white ring around each eye, and Neon does not. Is this from dirty water? Less than a week ago he was in dirty water when I rescued him, so that could explain it. I'll try to post pics as soon as I can! His tank is 1.5 gallons, not filtered. I do 100% changes every other day.
EDIT: I got a pic! Sorry it's not that good, but his tank has water stains so it's hard to get a picture of him that isn't blurry. I just stopped giving him 1 tsp/gallon of AQ salt because of finrot. Pic: