Infectious diseases are the major cause of economic loss in
commercial aquaculture [1]. In this regard, the aquaculture
industry began to focus on the prevention of diseases rather than
treatment with chemotherapeutants and antibiotics, the use of
which have been criticized for their negative side effects [2]. As
a consequence, many studies have focused into the modulation of
immune system in order to prevent the outbreak of disease.
Although vaccines promise for the prevention of fish diseases in
future, many vaccines are not effective against important diseases
[3]. Therefore, there arises a need for exploring other methods of
preventing disease, one of which can be immunostimulation
through alteration of the composition of fish diet and feeding
practices as well as immersion or via injection.