1. Oviparity:
- Oviparous fish lay eggs that develop externally outside of the female's body.
- The eggs are usually fertilized by the male's sperm after being laid.
- Examples include many bony fish species such as salmon, trout, and zebrafish.
2. Viviparity:
- Viviparous fish give birth to live young that develop internally inside the female's body.
- The embryos receive nourishment from the mother through a specialized structure called the placenta or through the yolk sac.
- Examples include some shark species (such as the spiny dogfish) and some livebearer fish species like guppies and mollies.
3. Ovoviviparity:
- Ovoviviparous fish are similar to oviparous fish in that they lay eggs, but the eggs hatch and the young develop inside the female's body before being born.
- The embryos receive nourishment from the yolk sac rather than a placenta.
- Examples include certain shark species (such as the swell shark) and some species of seahorses and pipefish.
4. Parthenogenesis:
- Parthenogenesis is a rare form of reproduction in fish where a new organism develops from an unfertilized egg.
- The offspring are genetically identical to the mother.
- This mode of reproduction is observed in a few fish species, such as some species of mollies and platyfish.
It's worth noting that the method of reproduction can vary among different fish species, and even within the same family, there can be variations in reproductive strategies.