You Newb.
The vast majority of fish species lay eggs that are then fertilized by the male,some species lay their eggs on a substrate like a rock or on plants, while others scatter their eggs and the eggs are fertilized as they drift or sink in the water column. Some fish species use internal fertilization and then disperse the developing eggs or give birth to live offspring. Fishes that have live-bearing offspring include the Guppy and Mollies or Poecilia. Fishes that give birth to live young can be ovoviviparous, were the eggs are fertilized within the female and the eggs simply hatch within the female body, or they can be viviparous, were the female supplies nourishment to the internally growing offspring. Some fish are hermaphrodites, where a single fish is both male and female and can produce eggs and sperm. In hermaphroditic fish, some are male and female at the same time while in other fish they are serially hermaphroditic; starting as one sex and changing to the other. In at least one hermaphroditic species, self-fertilization occurs when the eggs and sperm are released together. Internal self-fertilization may occur in some other species. One fish species does not need sexually reproduction to produce offspring; Poecilia formosa can use parthenogenesis for reproduction, were unfertilized eggs develop into embryos that produce female offspring.[4]