I take my biggest zebra danio out of the tank during feeding time since he's quite the food-hog. I let him swim into a plastic dish and then set it on a nearby table, covered with a dark-green plastic plate while I feed the others. I feed him, then put him back into the tank.

I've noticed that right when he re-enters the tank, his stripes are paler than usual. He swims around a bit, and the color returns within about 2-4 minutes. What causes this? I've thought of two explanations: lack of light in the dish, or separation from the group.

And, after feeding time, I've also noticed that a couple of the zebra danios each have two small, almost clear "whiskers", one on each side of their mouth. Before meals, the "whiskers" don't appear to be there, but they come out after they're fed.

What are these?

I'm no expert and may well be corrected but I presume that the fading colouring is caused by stress from being removed from the tank.

http://www.fishpondinfo.com/danio.htm

According to this website all danios have barbels, or "whiskers". But sometimes they hold them close to their body like when they swim fast. I noticed that too, I can't always see the barbels on my glofish but other times I do.

That's a good resource on danios, thanks Kristi! Good to know the barbels are normal. Interesting, on that link, it said that usually one large female will dominate over the whole tank....... sounds exactly like my "big bully" danio! I guess it's a she.

lclayton~ That sounds like a reasonable cause. I'm not especially worried about it, since the fish returns to normal. I do my best to keep his time in the dish to a minimum, and not stress him out by chasing him with the dish.

To any other people reading this thread, please respond with your two cents!