How does color affect water temperature?

Color of what? If it's water, then it's not pure water, and it probably affects the rate of absorption of radiation from the sun.

red and blue

Color effects temperature because light is absorbed and reflected based on an object's surface color, black absorbes more heat because it is a darker color and has less albedo (closer to 0) unlike...

no

Yes. Any temperature that does not suit the fish will obviously cause the fish to feel uncomfortable/unwell. If the fish feels unwell then you can expect it to loose colour. Most living things are...