Guppies (Poecilia reticulata) are one of the most popular, diverse and easy-to-keep freshwater aquarium fish to raise, and savvy breeders will understand the gestation period of guppies so they can be prepared for a large family of guppy fry.
Is My Guppy Pregnant?
Female guppies can get pregnant as early as one month old in a warm tank, although the usual maturity age is three months. The key to understanding a guppy's gestation period is knowing if she is, in fact, pregnant. It may be difficult to tell if a guppy is pregnant right away, although the gravid spot - a dark spot near the anus at the back of the abdomen under the tail - will darken and enlarge in pregnant females. A pregnant guppy will also appear to grow larger with a bulky, boxy shape, but this may not be apparent until near the end of her pregnancy. Toward the end of the pregnancy, the small eyes of the fry may also be visible through the female's thin, translucent belly skin, particularly near the gravid spot.
The Guppy Gestation Period
The gestation period for guppies will vary based on the female's health, her stress level, and the conditions of her tank. Gestation may last from 21-30 days, although 22-26 days is average for most guppy pregnancies. A warmer tank - between 72-79 degrees Fahrenheit - is best for gestation and will keep the female from being pregnant too long. If she is stressed or feels there is danger, she may stay pregnant longer, although excessive stress can also shorten the gestation period and cause a miscarriage or spontaneous abortion. To protect the female during her pregnancy, the tank should be kept at a consistent temperature and cleaned regularly to avoid any illnesses that can affect the development of the fry or the success of the pregnancy. A healthy diet is also essential to ensure healthy guppy babies.
Guppies Giving Birth
Toward the end of the gestation period, guppy breeders may choose to move the female into a birthing tank to protect the fry when they are born. A stressed or hungry female may eat her own fry, and guppy fry are a delicacy to many other fish. If a breeder has been able to keep track of the dates of the gestation period, it can be easy to know when to move the female to a birthing tank. However, it should be noted that doing so can also cause stress that might harm the parent or fry. When the female is ready to give birth, she may grow still and slow in the tank or seek out a solitary spot, but these are not always reliable indicators of the impending birth. It may take a few hours for the female to drop all the fry, and one drop can have as few as two to as many as 200 fry at once, although the average is for a female to give birth to 30-60 baby guppies with each pregnancy.
Starting the Gestation Period Again
A female guppy can become pregnant again just hours after giving birth, which has given these highly fertile fish the nickname "millionfish." Female guppies have the ability to store sperm from males for up to a year and can have up to eight pregnancies from one insemination if they are healthy and have good tank conditions. Since these fish can get pregnant so young and may live up to three years, and because the gestation period for guppies is just under a month, a single female guppy may have 2,000 or more babies in her lifetime. By understanding her gestation period and the best way to care for a pregnant guppy, fish hobbyists can enjoy raising these fish for years to come.