Future prospects for prophylactic immune stimulation in crustacean aquaculture - the need for improved metadata to address immune system complexity.

•Developments in the prophylactic immunostimulation of crustaceans have slowed.•Currently success is determined by immune effector responses.•Current approaches ignore complexity in PRPs and the gut microbiome.•Future research should consider this complexity in identifying novel solutions.•Recommendations for minimum reporting standards for metadata are made.