Friedrich M., 1998. Impact of the colour of aquarium on the levels of Acth and cortisol in the blood of carp (Cyprinus carpio L.). Acta Ichthyol. Piscat. 28 (1): 67-73.
A 14-day-long stay of carp in blue, yellow, and red aquaria caused statistically significant increase of ACTH and cortisol in the blood of the fish studied, compared to the initial state and to the aquarium in natural colours.