The majority of fish reproduce by spawning, a process in which the female and male fish release eggs and sperm simultaneously in a protected environment with or without a complex courting ritual. Some spawners build nests to guard the fertilized eggs.
Apart from building a nest, some spawners carry their embryos and their young around with them, while some, like the substrate spawners, scatter the eggs in the environment and do not guard the eggs or their young after spawning.
Live-bearing fish, which make up about 1 percent of all known fish species, mate to reproduce. The male inseminates the female through a modified fin called a gonopodium. The female livebearer stores the male's sperm and produces several broods of young fry, or newborn fish, from this single insemination.