Molly Swordtail Fish: An Ultimate Guide To For You

The Molly and Swordtail Fish is one of the most beautiful and weird-looking fish in the world. It is a member of the livebearer fishes and can be found in both fresh and saltwater habitats. This fish is not only beautiful, but it also has some pretty cool features that make it an interesting pet choice. In this ultimate guide to the Molly Swordtail Fish, we will discuss its features and how to let them breed.

Do Swordtails And Mollies Differ In Any Way?

If you’re looking for a fish that is neither too big nor too small, the swordtail might be a good choice. This fish has an average length of six to eight inches and can weigh up to four pounds. Swordtails have a triangular-shaped body with sharp, pointed fins on each side. 

On the other hand, Molly fish are more rounded and have smaller fins. In addition, they’re slightly larger than swordtails, measuring an average of nine inches long and weighing two to three pounds. The main difference between swordtails and mollies is their color – the molly’s are usually light brown or gold, while the swordtail’s fins are typically dark blue or green.

Can A Molly And A Swordtail Breed?

Livebearer (Family Poeciliidae)
Livebearer (Family Poeciliidae)

People have different perspectives and experiences when it comes to breeding molly and swordtails, and they share their own stories. Most people think that these two species are incapable of interbreeding; serious problems might arise if they did. Below are a few reasons why this is the case.

Different Families

Firstly, they belong to different families, so it is impossible to interbreed because of their different age groups and genetic factors. They both produce live young, yet fish mollies are Poecilia, and swordtails are Xiphophorus. Crossbreeding is not permitted outside of their families as a general rule.

Mollies Who Get Impregnated By Swordtails Can Die

A significant reason is that interbreeding of these species usually results in fatal outcomes. A study has found out that a female molly will most likely die after being impregnated by a swordtail. Therefore, it concludes that they are incompatible, so you should avoid breeding them together.

Breeding Incompatibles

As some people have noticed, they got pregnant while they were a couple in the aquarium. It is one of the reasons people believe they can interbreed. However, we would like to point out that both mollies and swordtails can store the sperm in their bodies for quite a long time, and they can subsequently become pregnant using sperm from the original partner.

Mollies and swordtails are unable to interbreed, as you can see. You can choose which species to raise in the tank by reading the next part of this article.

Comparison of Molly Swordtail Fish Breeding Processes

Each individual’s breeding process has certain similarities and peculiarities. As a result, we’d want to go through these procedures in great depth so that you can comprehend them better.

Mollies can't breed with swordtails
Mollies can’t breed with swordtails


Mollies and swordtails, as previously said, are livebearer fish, which means that their progeny develops inside before giving birth to fry fish. Female mollies with internal fertilization can have eggs within after mating and keep them there until fry mollies are ready.

Both individuals have a similar breeding schedule, with offspring appearing around one month after the egg is fertilized. Mollies and swordtails are waiting for their fry to become self-sufficient and live on their own at this time.

Female swordtails and mollies have another trait: they can store sperm for a long period and fertilize eggs without the presence of a male in the tank.

In both cases, the breeding process is straightforward, and you are not required to intervene. You will notice when the male fish goes under the female and copulation begins. They will generally exhibit comparable pregnancy signs, such as hiding at the bottom of the tank and refusing to feed. Their larger abdomen will also be visible.

You must create a nice tank environment for your pregnant mollies and swordtails, adding required shelters and hiding plants. It is also beneficial to keep the water warm, as they feel calmer this way.


When it comes to breeding age, there is a significant disparity between the two groups. In general, females become fertile around 6 months, whereas males might take up to a year, depending on the species of molly being studied. In contrast, swordtails do not require as much time, and they are generally ready to reproduce when they reach the age of three months (or less).

Unlike mollies, swordtails frequently consume their newborn offspring. Make sure your swordtails are properly nourished before giving birth and transfer the fry to another tank to avoid this happening to them. In addition, you may add some attractive plants and create hiding spots for the fried chicken. It takes around 2 months for young swordtails to grow and can be kept in captivity with adult swordtails.

Video: Swordtail, Platy And Molly Livebearer Group Profile


Is swordtail a molly?

Swordtails belong to the same family as mosquito fish, guppies, mollies, and platies, a group of livebearer fishes.

Do swordtail fish have many babies?

Swordtails belong to the same family as mosquito fish, guppies, mollies, and platies, a group of livebearer fishes.

How big do swordtail mollies get?

A swordtail fish typically grows to a size of 6.5 inches. Males grow up to 5.5 inches in size, whereas females grow up to 6.5 inches. The males have long tails, which makes their size seem smaller.

Final Thought

In conclusion, the Molly Swordtail Fish is an excellent choice for a beginner fish keeper. They are easy to care for and are very social. These soft corals are available in a wide range of colors and will make a great addition to any aquarium in the house. Be sure to do your research before buying any fish and ask questions if you are unsure.


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