White/Grey Area Head of Cherry Barb? Fungus?

[cuse88]

My Cherry barbs in my 46 gallon planted tank all have a whitish/grey spot on their heads. It's not cottony, just a flat smooth area. The other fish in my tank are otos and 4 Banded Rainbows, none showing symptoms and the area has been there for around 2 weeks now. Maybe something I just noticed or the way my LEDs are hitting their heads.
Thoughts?

All parameters are 0 (ammonia, nitrite, nitrate) and ph is 7.8

 

[maxwellag]

I think it's probably just a reflection. I found similar looking markings on others in pictures I found elsewhere. If you want to confirm this, you could catch some of them, put them in a container for a few minutes and view them with different light and from different angles.