Pelagophiles are an ecological group of fish that sweep eggs into the water column (herring, cod, some carp). The buoyancy of the eggs is provided by the swelling of the shells and an increase in the volume of eggs in the water.

Eggs and free embryos develop by floating freely in the water column, usually in conditions favorable for breathing. This group includes almost all types of herring, cod, flounder, some carp (chehon, silver carp, cupids, etc.).