Visual illusions as potential enrichment tool for captive fish.

The purpose of the thesis is to develop new effective tool for the enrichment of fish, an animal that is increasingly used in several areas of our society: from the food sector to the field of scientific research. These animals, along with the ones kept as pets, live their life in captivity, a condition that could lead to serious suffering and health consequences. After an initial overview of the cognitive abilities of fish, to better understand the complexities of a mind so different from ours, and a panoramic on the legislations and ethic perspectives regarding the life of captive fish, the experimental section tackles two main aspects of the enrichment, necessary to improve the conditions of well-being: the physical and the social enrichment. In the two sets of experiments, some promising results indicate the possibility of using visual illusions as an effective enriching tool to improve the life of captive fish and at the same time to study their perceptual systems.