Here's why:
* Biological Sex: Fish, like many animals, have distinct biological sexes determined by their reproductive organs.
* Female Fish: Female fish produce eggs. They are often referred to as females or spawning females.
* Male Fish: Male fish produce sperm. They are referred to as males.
In summary: Instead of "girl fish," you can use terms like female fish, spawning female, or hen fish (though that's less common).