In contrast to terrestrial animal production, pathogen transmission in aquaculture can be aided by fluid motion or hydrodynamics. Water movement can transmit freely-moving pathogens from an infected host to fishes, prawns or shrimps in the same cage and even to hydrodynamically connected discrete farms. Pathogen transmission is also aided due to high density of fishes, prawns or shrimps increasing the number of potential susceptible hosts. The ease of disease transmission calls for effective vaccines, which can be efficiently produced in high titres using Esco VacciXcell adherent cell culture bioreactors.