Turbot (Scophthalmus maximus, Psetta maxima) aquaculture is a
steadily growing industry with a production of approximately
77,000 t in 2013 [1]. However, intensive production of marine fish
larvae is still hampered due to high and unpredictable survival rates
[2]. These mortalities are often pathogen-associated [3] since the
immune system of the larvae is not yet fully developed [4e7].
During these immune compromised early stages, which especially
in marine larvae can comprise the first 2-3 months post hatch, the
larvae rely solely on the innate immune system, whilst the adaptive
arm is not fully established [7]. This limits the number of potential
treatments as well as prophylactic methods against pathogens as
vaccinations are not applicable until the acquired immune system
is matured and antibiotics are problematic due to environmental
aspects. However, the use of immunomodulators in larval culture
could present a potential method to increase immunity and survival
as they enhance the non-specific, innate immune system [8,9].