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swordtail-fish-not-breeding

Why Swordtails Not Breeding? – Wojciech J. Płuciennik (CC BY-SA 4.0)

As an aquarium owner, it is your wish to see the female swordtails grow and give birth to healthy live births.

Though not easy to identify, you may feel the urge to remain vigilant in order to ascertain whether the pets are mating or not.

Healthy and sexually active swordtails should deliver after a period of around four weeks after mating. They are able to give birth to around 10 to over 100 live fry at a time.

However, many aquarists find themselves in crossroads when it comes to why their swordtail fish are not giving birth. In reality, there are a number of factors that can make your swordtail fish not to give birth. Conditions such as inadequate water level and poor temperature can inhibit breeding.

On the other hand, in case your big boys are not infertile then the female swordtails may be giving birth to livebearers but due to lack of hiding spaces, the young ones are cannibalized by the bigger pets including their maternal mothers.

That is not the end of the list. There are some other reasons that are clearly captured in this article. So let’s keep the ball rolling.

Breeding Swordtail Fish

Before delving deeper into the nitty-gritty of this topic, it is prudent to develop some understanding of the breeding itself.

Unlike other tropical fish species, swordtail fish are hardy and usually breed easily. They have a gestation period of 28 days, meaning in a year, with healthy and sexually mature females, you can be sure of five hundred plus fry. However, this depends on factors such as stress elimination and the availability of quality food.

Once you have mixed the male and female swordtails in the aquarium, they will intermingle and mate freely without any hitch. Sometimes, it is the alpha-male that mates with all the female swordtails in your aquarium. The mating itself is fast-paced and may not be easily recognized.

Some other times, you will realize that the female swordtails give birth so often. In fact, they may not need to meet their normal 28 days gestation period. It is therefore of great importance to feed sexually matured females with quality food so often. This will also help them to give birth to lively and healthy fry.

Infertility in Swordtails

Besides the elongated lower tails, male swordtails are endowed with gonopodium as a primary sexual characteristic. The organ, found in many livebearers, is the force behind insemination. It is the alternative to andropodium that is found in halfbeaks.

An andropodium is not that advanced as gonopodium. It looks more like a bent anal fin with some hooks attached to it. Its primary role is to grab and secure the female during insemination.

On the other hand, the gonopodium is advanced and impressive in nature. It forms a long tube with hooked ends. It has a sensory apparatus used by the males for direct insemination.

It is worth noting that some swordtail varieties have overly enlarged fins with gonopodiums that are way too long to function. As such, they are rendered infertile. Therefore, with male species such as Lyretails, you can keep your female for as long as four years without any indication of female pregnancy.

Infertility in swordtail fish can also be caused by damage to the gonopodium. In such a case, the organ will lack the hold-fast mechanism hence rendering it faulty. Such damages can be caused by injury, disease or microscopic infection of the caudal fin.

In the case of male swordtail infertility, you can adopt artificial insemination or replace the existing males with others.

Inadequate Water Condition

Good aeration, water movement, appropriate water changes, and abundant quality food ensure a great chance of success in swordtail breeding. The pets should be feed at least twice in a day while at the same time maintaining cleaner and clear water for outstanding pets’ health. Inert water conditions and poor aeration results to death of the pregnant swordtails or unhealthy fry that die immediately after birth.

Foods such as baby brine shrimp usually foul the water quickly. Therefore, if the water is not changed, the pregnant swordtail may suffocate and die before or immediately after birth. This also happens with a quick ammonia spike.

Sex of the fry is dependable on the pH level. In a low or high pH, most live births end up being male while at a neutral pH, 50/50 ratio of male to female is produced. That is why there are more male swordtails in places like Florida, where the water is very saline.

Generally, maintaining a subpar water condition leads to stress that can result in the death of the females during pregnancy.

Inadequate Water Temperature

Temperature is the single most important prerequisite in maintaining the immune system of your pets. The pets in the aquarium are very sensitive to temperature and any change can affect their health for the worst. Any drop in the aquarium temperature results in increased pets’ vulnerability to diseases such as Ich. High temperatures due to malfunctioning or miss-set heater also result in vulnerability to diseases due to stress. Fry born of sick mothers do not usually survive since the disease is passed to them.

Upon introducing any swordtail fish in a new environment, it is advisable to acclimatize them. Fix the aquarium’s temperature by changing the water out and regulating the heating aspect of your heater. While changing the water, turn off the light and take the top off while slowly lowering the water level to prevent jumping.

Male to Female Ratio

Just like any other animal, female swordtail fish needs the male ones for mating. However, they develop preferences for specific males due to their body size and skin color. According to research, females prefer large-sized alpha-males for mating. But, in most cases, they are usually confused when it comes to judging the male sizes based on the sword length.

According to research, upon mating, the female swordtails can keep into themselves male sperms for as long as six months. Meaning, with a gestation period of 28 days, they can give birth several times without mating. However, at long last, they will still need the big boys for mating.

So what happens when you keep only males or females in your aquarium?

Definitely, the females or males will lack opposite-sex partners to mate with. As a result, the females may be sexually active but unable to give birth.

It is advisable to keep the female to male ratio at 1:3. During the process of mating, males usually chase the females in the tank. With a huge number of males, females tend to be stressed up and may end up dying during mating.

Fry Being Eaten

Just like any other livebearers, swordtail fish lack maternal instincts. Therefore, they will end up eating their live births. In natural moving fresh water, the newly born fry are usually carried away by the flow of water thus eliminating the nurture traits in this species of tropical fish. So, when kept in a tank, the fish perceive the newly born fry as food. And, since they are omnivores, they usually end up munching their live births.

A sexually mature swordtail fish can give birth any time of the month. They may not necessarily require males for mating. Therefore, to prevent gobbling down of the live births, it is advisable to keep the pregnant swordtail fish in a separate tank.

You can easily spot a pregnant swordtail fish through the black gravid spots and bulging bellies. They tend to remain calm and in specific positions due to difficulty in moving.

Anyway, that’s not all. The younger swordtails look beautiful in nature. In several occasions, their coloration lures their mothers into eating them. You may need to separate them from the community tank immediately after birth.

How Often do Swordtail Fish Get Pregnant?

Just like any other livebearer, swordtail fish have a short gestation period of about 28 days. Under good aeration, water level, temperatures, ammonia level, and pH, and with a good diet, a sexually active swordtail fish can give birth after every month.

They are able to get pregnant just after giving birth. All you need is an ideal aquarium condition and, of course, fertile males.

How Many Fry can a Female Swordtail Fish Deliver at Once?

Swordtail fish can give birth to as many as 100 fry at once depending on the health status and genetics. On average, a healthy female swordtail will give birth to about 30 to 35 fry.

Based on the conditions in the tank, if born healthy, all the fry can survive to adulthood. However, with factors such as overcrowding, it is advisable to keep the newborn fry in separate tanks.

Why Did my Swordtail Fish Die After Giving Birth?

Many swordtail females die after birth due to stress. Being in labor is very stressful for the female swordtail fish. Tank mates or bad water parameters can also cause more stress for the pregnant female.

Even though everything seems normal, there could be complication while giving birth and fish can die.

Written by Fabian

Hey, I'm Fabian, chief editor at Aquarium Nexus. I really enjoy the aquarium hobby and love sharing my experience with others. If you have any questions feel free to contact me or leave a comment below.

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