Fishes turning red.

Question
A couple of weeks ago I bought fish food in the form of orange pellets. I trusted
the lady at the store and didn't care to read the side of the container. I later read
on the side that it was for parrot fish and that it could enhance those fish' color.

Anyway, a few days later, I began to notice a red coloration or hue in my tetras,
both bala sharks, and the albino angel. The other angel had a reddish hue in
both eyes.
After that, my goldfish developed red gills.
I knew that my tank was overstocked so I took the goldfish, the balas, and the
pleco back to the store.
Now I have a 40 GAL tank with 4 blackskirt tetras, 2 zebra danios, 2 angels and
a dwarf gourami.
They all seem well and are eating ok.
But all of them have that reddish hue on them, especially in their gills.
The ammonia is 0, and the nitrates are between 25-50. I'm doing 10-20% water
changes every other day.

It's been 5 days since I returned the other fish and I've been doing the water
changes, and I don't see any change in their color.

Could it be just the food? or are they infected?  

Answer
some food does change/enhance the color. My fish did a similar thing, it doesn't seem to hurt them or anything (unless it's red pest), even on the eyes. If you really are worried, just change the food but this is nothing to worry about unless there is:
rapid gill movement
fish glancing off decor
frayed fins
clamped fins