Abstract: A method of identifying fertilized fish eggs (200) in a sample of eggs (104) taken from a batch of incubating fish eggs is disclosed. The method includes the steps of treating the sample, within a period of time from initial fertilization of the batch, with a fixative (106) bringing an outer membrane of the eggs at least partly transparent and/or a blastodisc of the eggs at least partly opaque. The method further includes the step of capturing at least one image of individual eggs of the sample depicting the blastodisc of the egg, analysing the at least one image for detecting divided cells in the blastodisc, and identifying each egg associated with an image showing divided cells in the blastodisc as a fertilized egg. An associated system and a fish egg analysis apparatus are also disclosed.