Clowns also come from Kalimantan, and the fish from here are basically like Sumatrans, but have more intense red coloration. The source article for this information states that Sumatran fish have a kind of silver sheen to the body not seen in Kalimantan fish. This is a term we've come to use here as a description of one particular color mode seen in our fish. New owners of Clowns are always posting panicked messages, assuming that there's something drastically wrong with their new fish. Usually, there is no problem at all.
Clowns are able to change their coloration within certain parameters.
These changes can be based on mood, aggression, possibly stress and other factors. The illustration shows a fish sitting at a slight tail-down attitude with fins spread. Depending on one's tank lighting, this color change may show a kind of greenish, metallic sheen to the whole body, most noticeable over the stripes. The edges of the stripes tend to have a sort of paler area than the rest of the stripe. However, once in a while, some fairly funky variations are seen.