carpet nem color
 

what is the actual difference between the different colors? i bought a green but if i change the food he changes color. with krill hes light pink and with reef roids in the tank( which im asuming hes eating he turns to a hot pink around the outside. how come

Carotenes can produce vibrant colors in fishes, and are a common component in 'color enhancing' fish foods. The mechanism could be something along those lines (coloration from different components in different foods), or like nudibranches that take on the color of whatever coral (anemone, algae, whatever) that they feed on.

Mine have never really changed colour that dramatically. I sometimes see different subtle hues but the overall appearance rarely changes. Can you post some pictures of the differences? I'd love to see this. That's kinda cool.

What species of carpet?

not a clue on the species but ill try and post a pic in the next few days