How Do Guppies Give Birth?

Mychelle Blake
Contributor: Melissa Mayntz
Photo of a guppy giving birth

Guppies (Poecilia reticulata) are livebearers, which means these fish give birth to live, viable, free-swimming young instead of eggs that still need to mature. Understanding how guppies give birth can help aquarium enthusiasts enjoy breeding healthy guppies without stressing the pregnant mother or risking the lives of the young fry (baby guppies).

All About Guppies Giving Birth

One of the first questions people usually ask is, "How do guppies have babies?" When a guppy gives birth, the females will "drop" 2 to 200 baby guppies, called fry, typically in four to six hours. If she is stressed, however, the process to give birth to all the fry can take up to 12 hours. In extreme cases, a female guppy may give birth to just a few fry at a time, with pauses of several hours or days between births, although in most of these cases the young are not viable and die quickly. Typically, the fry are delivered one at a time, although they may appear in quick succession with pauses between groups of babies.

The baby guppies are usually born curled into small balls, just as they matured in the female's womb in this compact shape. They will uncurl and begin swimming quickly, however, and newborn guppies often swim upward if they are very healthy. Unhealthy, premature or stillborn young will sink.

When Your Pregnant Guppy Is Ready for Birth

Female guppies can become pregnant when they are just a few weeks old, and if they are not separated from male guppies they can give birth on average once a month for several years. Guppy breeders quickly learn to recognize the signs of a pregnant guppy, including significant weight gain and the darkening of the gravid spot near the anus under the tail. The gestation period for guppies is from 21 to 30 days (22 to 26 days is average) depending on the tank's temperature, cleanliness, and the female's health. Near the end of that gestation period, the female will show signs of the impending birth.

Pregnant Guppy Signs of Delivery

Different fish have different personalities, and not every female guppy will show the same signs she's ready for the delivery. Watching for the following clues can help you know when the time for birth is drawing near.

  • Boxy, squared-off look to the female's abdomen
  • The gravid spot is very dark maroon or black
  • She grows still in the tank or seeks a place to hide
  • Change in eating habits, such as refusing to eat or spitting food out
  • Shivering or shuddering motions during contractions
  • Increasingly rapid breathing

When a female guppy shows indications that she is ready to give birth, it can be a good idea to move her to a birthing tank or net inside the normal tank or in a completely separate tank. This will separate her from the other fish in the tank so she does not need to exert herself avoiding from them. Birthing tanks also frequently have partitions that give the fry a safe place to begin swimming - fry are a delicacy to many fish, including the hungry mother.

DIY Birthing Tank

A simple way to make your own birthing area to keep the pregnant guppy safe is by using a small plastic soda-type bottle.

  1. Cut the top of the bottle off, leaving a strip about one inch thick and three to four inches long sticking out from the bottom half.
  2. Use a hair dryer or other heating element to bend the strip out and down so that it makes a "hook."
  3. Punch holes into the bottle with a small knife.
  4. Place the bottle into the tank, using the hook to secure it to the top of the tank.
  5. Place the fry inside the bottle. This way they can swim inside and water from the tank will fill the bottle while the bottle itself protects the newborns.

Helping Guppy Moms and Newborn Guppies

After giving birth, the female guppy should be kept in a quiet tank for at least several hours so she can recover her strength and energy before joining the rest of the fish, and she should be well fed to help her recovery. If the batch of fry was exceptionally large, she may need up to a full day or two to recover sufficiently, but isolating her for longer periods can be too stressful.

Keeping Guppies Safe in the Communal Tank

Newborn guppies, although they can swim quickly, are at risk in a tank with other fish because they can easily be eaten by any fish species, and even by their mother. Placing a variety of floating plants with roots near the birthing tank or throughout the tank where the fish will live offers the fry a place to hide, and plants can be either real or plastic. Ideally you want the plants to be clumped together to give the fry a safer place to hide. Keep in mind that fry can still be eaten with this method. Any dead fry should be removed immediately so they do not create excessive waste or toxins in the tank, and the remaining fry should be fed an appropriate diet for fast, strong growth.

Keeping Your Tank Habitat Safe

The tank should also be kept at an appropriate temperature, usually between 72-79 degrees Fahrenheit, and it should be cleaned regularly to prevent the buildup of waste which can make the fry sick. Clean the tank for any signs of algae and do a 25% water change weekly. You may also need to add a sponge filter to your tank which ensures the fry do not get stuck in the filter. A simple DIY option is to attach a fish net over the filter opening which allows water to pass through but keeps the fry from being sucked into it. Finally make sure the fry get enough light which is necessary for optimal healthy growth. Approximately 8 to 12 hours per day is enough for the fry and you can use a tank light or the ambient room light if it's bright enough.

Keeping Guppy Fry Safe Through Separation

In addition to providing plants to give the fry hiding spots, you can keep the newborns safer by keeping them in a separate tank or a closed off area in the tank. Remove the mother from your birthing tank or area as soon as she is finished giving birth to all the fry.

  1. If you don't have a separate tank, you can use a bucket with water from the regular tank.
  2. Place plants in the bucket, such as water lettuce, which will remove the need for a filter.
  3. The guppy fry can be moved to another tank in once they are safe from the mother.
  4. Another method is to place a small piece of mesh in a birthing tank, splitting the tank into two areas.
  5. The guppy fry can swim into the other area to be safe from the mother who can't pass through the mesh.
  6. You can also buy a pre-made mesh net box which hangs on the side of your tank and allows water to pass through but keeps the fry safe from other fish.
  7. Do not add the fry back into your regular communal tank until they are at least a half-inch long.

Enjoy Baby Guppies

Knowing how guppies give birth and how to care for both the pregnant female and the newborn fry will help guppy enthusiasts enjoy regular births of strong, healthy fish they can appreciate for years.

How Do Guppies Give Birth?