Studies concerning the effects of stress on the immune systemof fish
have focused on systemic immune responses; mostly hematological
parameters. Furthermore, some studies have shown how stress leads
to increased disease susceptibility due to immunosuppression in fish
(Iguchi et al., 2003; Tort, 2011; van Kemenade and Chadzinska, 2009).
One of the most evident responses of fish to stress is the production of
copious amounts of skin and gill mucus (Shephard, 1994; Vatsos et al.,
2010). Thus, gross observations of stressed fish indicate that the mucosal
barriers of fish are important sensors of stress.