Sorry if this a repeated question. What is the deal with the color or FBT's? I am looking for some in my area, there seems to be a shortage but what is left are all dark colored. I have read a little bit our their color but can't find any consistent info.

Does their color change due to environment - temp, light, color of substrate. Does is have to do with sex and breeding? Age?

If I buy the darker color ones, what can I do to color them back to bright green?