An egg is the egg cell of a fish. They differ in shape and color. They can be spherical (absolute majority of fish), oval (hamsa), cigar-shaped (gobies, rattan), drop-shaped and cylindrical (some gobies). The eggs of sturgeon are black in color, green in gobies, and yellowish and orange in the vast majority of fish.

The size of eggs in fish varies from 0.6 mm, particularly in tulka, flounder, and sandfish, to 7 mm in salmon, chum salmon, catfish, and others. Groups of eggs connected with each other with the help of mucus, can have the form of clumps, ribbons, cords.