Free embryo - embryo from the moment of leaving the shell until the moment of transition to mixed feeding. It is a sub-period of fish development.

The embryonic period of fish development continues for some time after hatching, while the pre-larva, or free embryo, which possesses a number of embryonic features of the structure of respiratory organs, circulation, digestion and other systems, passes through the final stages of embryonic development. When the gill, digestive and other systems begin to function, the activity of the embryonic organs ceases and the period of embryonic development ends.