Best Ever Q&A Space Our World Nature Evolution Prehistoric Life Dinosaurs Simple Creatures Insects & Spiders Fish Amphibians & Reptiles Birds Sea Mammals Land Mammals Ecology Animal Behavior Pets Farm Animals Plant Kingdom Plant Life History Science & Technology	Do all fish lay eggs? No. Several species, such as the sailfin molly, keep their eggs inside until they hatch. Then they give birth to as many as 200 live young.   Previous: Back Book: Best Ever Q&A Section: Nature Chapter: Fish