Guppies are ovoviviparous fish, meaning their reproductive method falls between oviparity (egg-laying) and viviparity (live-bearing). Their specific characteristics are as follows:
1. Reproductive Method
Internal fertilization: Male guppies use their gonopodium (a modified anal fin serving as a copulatory organ) to transfer sperm into the female’s body for fertilization.
Internal development: Fertilized eggs hatch inside the female’s body. Fry (baby guppies) absorb nutrients from their yolk sacs while developing and do not rely on a placental connection to the mother.
Direct live birth: Once development is complete, the female gives birth to free-swimming live fry instead of laying eggs.
2. Differences from Viviparity and Oviparity
Ovoviviparity (Guppies): Fertilized eggs hatch inside the mother. Fry can swim freely at birth. The mother only provides protection and no additional nutrients.
Viviparity (e.g., Mammals): Embryos obtain nutrients directly from the mother through a placental connection.
Oviparity (e.g., Goldfish): Females lay eggs first. Fertilized eggs then develop and hatch entirely outside the mother’s body.
3. Reproductive Traits
Short reproductive cycle: Guppies reach sexual maturity quickly, usually in about 3 months. Their gestation period lasts approximately 22–28 days.
High fecundity: A single female can produce 10–120 fry per birth. When the water temperature is suitable, they may reproduce once a month.
High fry survival rate: Direct live birth helps avoid the risk of eggs being preyed on by other fish, which improves the fry’s survival rate.
4. Precautions
When breeding guppies, it is recommended to isolate pregnant females. This prevents adult fish (including the mother) from eating the newly born fry.
Fry should be kept in a separate tank, or dense aquatic plants should be placed in the tank as hiding spots. This helps them avoid being attacked.
Summary
Guppies are ovoviviparous fish that combine partial traits of both oviparity and viviparity. They have high reproductive efficiency, making them a great choice for beginners who want to experience the fun of fish breeding.