I saw this work of art while I was queueing up for fish and chips and thought I would take a video for the blog. The fish is illuminated by a light that changes colour. Different wavelengths are diffracted by different angles so you get a spectrum.You can see the effect of that in the region marked by the green arrow. But is this what we would expect? Not entirely. Notice how the different colours appear at the same angle. The white arrow points to a region where the spectrum (a line spectrum) is static. This must have been due to the reflection of a white light source not the changing one. The green arrow points to a region where there is only one line in the spectrum. Other regions show different colours.

Something fishy is going on.

The fish and chips were very nice although the portions were too large.