Fish Reproduction

• Oviparity is the deposition of eggs
• Viviparity is the birth of a fully formed individual
• Ovoviviparity is when the eggs are fertilized and develop inside the mother
• Spawning is when  a large group of adult fish come together to release their gametes into the water at the same time. ​
• Spawning means that many embryos will form at once, which helps ensure that at least some of them will be able to escape predators.​
• With spawning, there is no way for fish parents to know which embryos are their own. ​

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  Therefore, fish generally don’t provide any care to their eggs or offspring. ​
• The 3 stages of development are

  1. Eggs
  2. Larvae
  3. Fry
• Eggs

  Most eggs do not survive to maturity even under the best conditions. Threats to eggs include changes in water temperature and oxygen levels, flooding or sedimentation, predators and disease.​
• Larvae live off a yolk sac attached to their bodies. When the yolk sac is fully absorbed, the young fish are called fry
• Fry undergo several more developmental stages, which vary by species, as they mature into adults. Young fish are generally considered fry during their first few months​
• Spawning: Female fish release eggs into the water (either into the water column or into a nest) and male fish fertilise eggs by releasing milt. Not all eggs are fertilised. Some fish spawn each year after reaching maturity, others spawn at intervals (every four years, for example), while others spawn only once and then die.​
• Line breeding is the process of breeding two closely related Fish to produce offspring with the desired characteristics.
• Line Breeding

  A) C

  B) A

  C) A

  D) A

  E) D

  F) E

  G) G