Most fish species lay eggs, but there are a few exceptions. Livebearers such as guppies, mollies, platies, and swordtails give live birth to their young instead of laying eggs. Goby fish can lay eggs in seawater but give birth to live young in freshwater. Sharks and rays also give birth to live young, with the eggs hatching inside the female's body. These unique adaptations allow for a diverse range of reproduction methods among fish species.