Bacterial diseases are known to be an important constraint in the further
progress of shrimp culture throughout the world [1]. Vibrio parahaemolyticus
and V. harveyi are reported as pathogenic agents in penaeid species [2–5]. The
need for alternative methods for regulating the number of pathogenic bacteria
has led researchers to methods of treatment such as probiotics and immunostimulation
[1]. Immunostimulants aim at enhancing the non-specific defence
mechanisms in animals, including shrimp [6].