Not Sure If Barb Is Sick

I have a tiger barb that is turning reddish around his head and tail and on top of is head is a little green. Anybody have an idea?

Size of tank in gallons or lites.
How many fish and which type.
Water stats in ammonia, nitrite, nitrate, and ph.

Is the white patch on the glass on the fish.
Red patches can be due to parasites or bacterial.
Any signs of flicking and rubbing.
Any red edging to the tail or red streaking, red patches can be septicemia.

He is in a 10 gal. tank with 5 other tiger barbs

Water stats.
-pH = 7.0
-Ammonia = 0
-Nitrites = 0
-Nitrates = 20

He doesn't show any signs of being sick except for the discoloring. He swims around no problems, doesn't hide, not rubbing up against anything, no signs of trouble breathing, eats with no problems, no sudden or eratic movements. The red doesn't seem to be as bright today, but the green spots haven't changed. As for the white spot that is just a glare from the tank.

Post in the right part of the forum just to make sure its not normal.
Never kept tiger barbs so couldn't tell you if its normal, green on tigar barbs is normal.

Now I'm going to really show how much of a novice in the fish world I am, turns out that the fish a have that I thought were tiger barbs are actually ruby barbs. The green on its head was always there it just nomally appears more of a black, but with the fish turning red it appeared more of a green. The fish turned red because it was looking to mate. Ruby barbs turn red as a mating call. Putting it out there in case anyone else ever has the same problem, and to Wilder thanks for trying to help.

Glad you found your answer.