Fertilized teleost fish eggs are a complex formation, in which dividing cells are located in a small point in the entire volume of eggs. Isolating embryonic cells can be considered a necessary step in the research of developmental peculiarities of fish cells at the earliest stages of embryogenesis before embryo formation. The main advantages of the offered protocol are rapid isolation, no enzymes, and overall low cost compared to other protocols. The protocol is suitable for the isolation of embryonic cells from medium-sized eggs at the stages of blastula or gastrula, for studies in a variety of applications (e.g., microscopy, flow cytometry, and other methods). Fertilized nelma eggs (Stenodus leucichthys nelma) are used in the protocol as a model. Key features • Fast and cheap isolation of cells from fish eggs at early stages (blastula or gastrula). • Applicable for most of the methods for cell study (any staining, microscopy, flow cytometry, etc.). • Can be applied to other teleost fish eggs with medium egg diameter of 3-4 mm. Graphical overview.