Guppies or Poecilia reticulata are fascinating freshwater fish that originate in Northeast South America. These creatures are highly adaptable and a popular choice for tropical fish enthusiasts. If you are lucky to have several of these fascinating fish, you might wonder whether or not your females may lay eggs.
Guppies do not lay eggs; instead, they store their eggs within their body until the young are ready to swim, eat and fend for themselves. Guppies are called ovoviviparous, which means although they keep the young inside their bodies, they do not provide nutrients to the growing young.
If the conditions in your tank are ideal, you will find this hardy breed quite prolific breeders and soon find your tank filling up with new fry. The nature of guppy’s mating and birth is a captivating process for fish keepers and can be a rewarding experience. Please read on if you would like to know how guppies mate and bear young.
How Do Guppies Give Birth?
Female guppies are ready to give birth after 10 – 20 weeks old, and they can continue to reproduce for 2-3 years. The gestation period or pregnancy period varies but tends to fall between 20-60 days after fertilization. According to studies, the guppy may be ready for fertilization mere hours after giving birth.
The female guppy releases her young one at a time, and the fry usually emerges from her abdomen tail first. The guppy may still have the remnants of the yolk sac still attached and will absorb the rest of the yolk fairly soon after emerging from the mother.
Newly hatched fry is blackish or transparent and tends to settle on the substrate shortly after birth. The newborn fries have a slender body with jaws already developed and can swim, eat, and avoid danger. Typically the fries will start to search for food among the stones within an hour or two.
Guppies are not maternal over their live young, and the young are left to fend for themselves after birth. They have developed enough to swim and feed themselves. In fact, many guppies in aquariums have been found to prey on their own young, eliminating guppies entirely from the parents of the year award!
The guppy fries are fast-growing and reach sexual maturity at 8-10 weeks old. Generally, the fries will reach full adult size in approximately six months.
How Do Guppies Produce Young?
Guppies produce young by sexual reproduction in which the male inserts sperm into the female guppy by means of a gonopodium. The female guppy may store the sperm for several months to fertilize the eggs inside her body. The female then gives birth to live young.
Guppy females also exhibit polyandry, which describes females that mate with multiple partners. This mating behavior has evolutionary benefits for the female guppy as they have shorter gestation periods than mating with single partners, and their offspring exhibit better schooling and predator avoidance.
During the mating process, the male guppy fertilizes the female internally with bundles of sperm called spermatozeugmata. The gonopodium has a channel-like structure where the bundles of sperm are transferred into the female guppies.
When the female is receptive, the male briefly inserts the modified gonopodium into the female’s genital pore. However, opportunistic males may force themselves on the female by thrusting their gonopodium at its urogenital pore.
When a female is sexually receptive, they have the ability to store sperm, and studies have shown that they can have multiple births after only one mating. At the same time, the stored sperm may be fertilized at different times and give the female guppy the ability for several successive births in a single fish. This process is called superfetation.
Fish keepers can recognize if their female guppy is pregnant by the appearance of a black triangle between the anal and pelvic fins. This dark area is called a gravid spot and will darken and increase in size the nearer the guppy comes to birthing her young.
How Do I Know if My Guppies are Mating?
You will know that your guppies are mating by the male arching into an S shape and quivering near the female. The female will respond to the male by presenting her genital pore. The male thrusts his gonopodium quickly into her genital pore.
The male guppy displays a courtship ritual when approaching a guppy female and does a type of dance called a sigmoid display, and presents himself in front of his potential mate. The sigmoid display involves the male positioning his body in front of or alongside his potential mate and arching his body into an S shape and quivering.
Female guppies are attracted to more brightly colored males, and the male display presents his colors to their full advantage. Studies suggest that females are most attracted to the male guppies that stand out from the other males in terms of their coloration.
The female responds to her receptivity by exposing her genital pore for copulation. The mating is very quick, with only a second or so of interaction in order to transfer the sperm package to the female guppy.
However, not all guppy suitors are nice guys, and some indulge in sneak copulations where they insert their gonopodium regardless of the female receptivity. These male guppies engage in no courtship rituals or displays as one expects from a sneak!
In a sinister evolutionary development, male guppies have gonopodium claws, which is a pair of claws at the tip of the guppy’s penis. These claws aid sperm transfer, but the male guppies use them mainly to grasp female guppies resistant or unreceptive to mating.
With their whacky love lives, it’s no wonder that so many scientists use guppies for studies on mating and sexual behavior. Remember to separate your guppy fry from their mother and adult guppies after birth if you don’t want them to end up as lunch. Otherwise, it’s best to provide plenty of plants for hiding spaces if you intend to leave them in a planted tank.