The epidermis defines the physical separation between the internal
and external environment of fish and it is a primary defender of internal
homeostasis (Shephard, 1994). The skin of fish is an important first
barrier against pathogen entry and it is equipped with a mucosal
immune system known as SALT (Salinas et al., 2011; Xu et al., 2013).
Moreover, fish skin is colonized by a rich and diverse bacterial community
known as the microbiota. Disruption of skin barrier homeostasis
and dysregulation of skin commensals as a result of stress can potentially
explain the increased disease susceptibility thus far reported in
stressed fish. The effect of stress on skin homeostasis and skin bacterial
communities has yet to be investigated in fish. Our hypothesis is that
the skin and skin-associated bacteria sense and respond to stress
hormones released by the fish host