Cysts, in particular Artemia cysts, are incubated the in a hatching medium so that a portion of the cysts hatch and release free swimming live food organisms. The free swimming live food organisms have subsequently to be separated from the cysts which have not hatched. Before incubating the cysts, magnetic particles are applied onto the cysts so that these cysts can be attracted magnetically, in particular in the liquid hatching medium. This enables to separate the unhatched cysts and the empty cyst shells, coated with the magnetic particles, effectively from the free swimming live food organisms which do not have magnetic particles applied onto their outer surface. The invention also relates to the coated cysts.