Editing Round goby (section)

==Reproduction==
[[Image:Round goby eggs.jpg|thumb|left|Round goby eggs on rocks, [[Dniester Estuary]], [[Ukraine]]]]

Female round gobies reach sexual maturity in one to two years while males do so in three to four years. Gobies in the [[Laurentian Great Lakes]] typically mature up to one year earlier than in their native habitat in Europe. Females can [[Spawn (biology)|spawn]] up to six times during the spawning season, which spans April to September in most areas.

Males will migrate from deeper water, where overwintering occurs, into shallower breeding grounds during the beginning of the mating season. They then release a steroid sex pheromone that attracts females to their territory. Males also use visual displays, including posturing and changing color from beige to black during mating season, and can produce sounds during courtship. The females deposit their eggs in male-guarded crevices between rocks. Eggs are {{Convert|4 by 2.2|mm|in|abbr=on|sigfig=2}} in size, while egg clutches can contain up to five thousand eggs. Males are territorial and will defend eggs from predators as well as continuously fan them to provide the developing embryos with oxygenated water. This results in successful hatch rates of up to 95%.