This varies greatly between species.

Carp and catfish may breed once a year and produce in excess of 100 000 tiny eggs per female.

Tilapia may breed three to four times each summer and may produce 500-1000 eggs per spawning.

Guppies may give birth to 50-150 live young every six to eight weeks throughout the year.

Eels will never breed in freshwater, but go into the sea to breed in a manner still poorly understood even by scientists.