zebra danio whiskers?

[confusion]

I have 7 zebra danios that are a lot of fun to watch. I was looking more closely at them and I noticed that one has a whisker that starts at the back top of its mouth and protrudes down about 3mm or so. At first, I thought it swallowed a floating hair, but it certainly looks like its a permanent part of him. Is that normal? none of my other zebras have that?

 

[Apocalypse_Gold]

Danios have whiskers. Turn on the light in the middle of the night and you'll see them on the others as well. They usually only extend them at night or when breeding.