The present invention is a jetter assembly for cleaning aquaculture nets in situ. The jetter assembly includes a high-pressure rotational union connected to an outer shroud assembly and an inner washing ring assembly. The rotational union includes a hose inlet connected to a fluid hose, a shaft and a plurality of inner ring segments securing the rotational union to the outer shroud assembly. The outer shroud assembly includes several supporting gussets connecting the outer shroud assembly to the rotational union and several inner and outer shroud sandwich plates connecting several shroud sections. The inner washing ring assembly includes a manifold, several spray bars and a centrifugal vortex plate that generates a fluid vortex to clean the nets.