Acute stress alters intestinal function of rainbow trout, Oncorhynchus mykiss (Walbaum)

It is concluded that, under the present experimental conditions, acute stress causes cellular alteration in rainbow trout gastrointestinal tract. Ultrastructural damages are mainly observed in midgut, but most changes appear to be transient returning to normal levels within 48 h. Changes in adherent intestine microbial population level and compositions together with increased intestinal paracellular permeability following acute stress suggest a possible increased susceptibility to bacterial infections after stress and that active feeding may have a protective role.