The black Mary fish is neither oviparous nor viviparous. The way they reproduce is quite special, which is oviparous. When they reproduce, the male fish will put their genitals into the female fish's drainage hole, and then discharge sperm. At this time, the eggs will be fertilized in the mother. After successful fertilization, fish eggs will not be born immediately, but will develop in the mother for a period of time, and will not be born from the mother until they mature.

The obvious difference between oviparous and viviparous is the relationship between cub and mother. Viviparous animals connect mother and cub through umbilical cord, and cub also gets nutrition provided by mother through umbilical cord. Ovipartum is different. Young pups get nutrition through vitellogenin, and they have little contact with their mothers.

As mentioned above, black Mary fish are oviparous fish, so they do not produce much. Under normal circumstances, a black Mary fish can produce 40-100 small fish. Of course, there are also some Mary fish with strong reproductive ability, which can produce 200 small fish at a time. Although they produce a large number, their survival rate is not very high, so their reproduction number is not very high. Mary fish cubs have poor adaptability to the environment, so breeders need to prepare a stable and comfortable living environment for them.