It is most likely that fish DO see in color. Many fish respond to other fish when they breed. The breeding colors let other fish know when they are ready to breed or may be defending territory. If you have fish you will notice this with some species. Cichlids are especially colorful when they are breeding.
Fish do respond to colour, to make a fish more calm you might want to use soft colours like a brown or beige like a more natural one, if you want it to be kind of hiding and very edgy then get brighter colours like greens purples reds pinks...ext. It also depends on what colour your fish is, try to match the colour of your fish with the rocks to make it more comfortable so it will blend right in, also plants ans rocks work well.
Many fish have the ability to see color. Those that do see color have cones, the migrating fish like Shad or Salmon have eye receptors readily adapted which can see green in the ocean and red during spawning.
I saw a show on tv about this once and they proved that goldfish do respond to color.
Flatheads + whiting like red/pink.
Trevally like green.
Snapper like the green + pink/red.
And that's all I know
Trevally like green.
Snapper like the green + pink/red.
And that's all I know
Some fish do respond to color but not all fish