Platies are relatively small, live-bearing tropical fish originating in Central America. They are relatively low-maintenance and are easy to care for, making them ideal pet fish for inexperienced fish keepers. Breeding platies is also straightforward. In fact, if you place a male and female in a aquarium together, the chances are high that they’ll breed.
Get to Know Platies
Platies are part of the Xiphophorus genus within the Poecilliidae family of freshwater fish. These fish are characterized by their ray-type fins, their small size -- typically no larger than 2 inches -- and their status as livebearers. They are commonly referred to as southern platyfish or variatus. Several hundred variations of platy exist, but due to their popularity as aquarium fish -- and the frequency with which aquarium-bred specimens are released into the wild -- hybrid variations outnumber specific breeds.
The Start of the Process
Platies reach sexual maturity at around 4 months old. Males, who are slightly smaller than females in adulthood, have gonopodia -- otherwise referred to as anal fins -- with which they directly fertilize females. This is unusual: The majority of fish do not mate directly. Instead, females lay batches of unfertilized eggs, which males will fertilize at a later date. Male platies are very keen to reproduce. Some platy owners elect to have male-to-female ratio of 1 to 2. This limits risk of one female becoming stressed by constant harassment from the male.
Pregnancy and Gestation
The pregnant platy will behave pretty much the same as she does normally. There are no distinct behavioral changes to look out for. Like other live-bearing fish, she carries her fry until they are fully developed. The gestation period typically lasts for around 28 days.
When ready, the mother will swim to a quiet part of the aquarium, where she delivers her fry tail-fin-first. Platy fry can swim as soon as they are born. Adult platies don’t have any protective instinct toward fry; in fact, they may eat them. This is why it’s essential to remove the fry from the aquarium as soon as possible. To accomplish this, you must monitor the aquarium no less than every two hours to identify whether any fry have been born. They can be a quarter-inch long or less, including tail fin, so consider using a magnifying glass. Be sure to check underneath rocks.
Prepare a separate tank for the fry, a tank whose water matches the conditions of the water in which they were born. Use a plastic scoop or net to gently remove the fry and place them in the separate tank. Keep them in here until they are approximately the same size as their parents, then reintroduce them. If you don’t have room for a separate tank, use a breeder box to separate the adults and fry.
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Simon Foden has been a freelance writer and editor since 1999. He began his writing career after graduating with a Bachelors of Arts degree in music from Salford University. He has contributed to and written for various magazines including "K9 Magazine" and "Pet Friendly Magazine." He has also written for Dogmagazine.net.