the respiration rate will increase as temperature increases. An increase in temperature will minimize the amount of dissolved oxygen in the water and increase the metabolic rate of the goldfish, thus causing the goldfish's respiration rate to increase (“Hot waters make it hard for fish to breathe”).
To try and help although thee aren't any answers i would say... if they were to literally conduct a field study such as this, much pollution would occur, Millions of fish would die as of plants also. And would over-all Lake Michigan would never be the same again.
There is no pigment in the brain, so it is in it's natural colour, grey.