Do female fish lay eggs without male?

Yes, some female fish can lay eggs without a male, a process called gynogenesis. This occurs when the female's eggs are activated by external stimuli, such as environmental cues or contact with sperm from another species. Gynogenesis has been observed in several fish species, including some species of fish in the Cyprinidae, Salmonidae, and Poeciliidae families.

In gynogenesis, the female's eggs are essentially "tricked" into developing without fertilization by a male. The external stimulus causes the eggs to undergo cell division and development, resulting in the formation of offspring that are genetically identical to the mother. This process allows female fish to reproduce even in the absence of a male partner.

It's important to note that gynogenesis is different from parthenogenesis, which is a type of asexual reproduction where a female produces offspring without the involvement of any genetic material from a male. In gynogenesis, the female's eggs still require some form of external stimulus, while in parthenogenesis, the eggs develop and hatch without any external trigger.