Swordtail breeding: how to breed swordtails at home and what to feed the fry

Swordtails are one of the most popular and undemanding fish for home aquariums. Their bright colors and lively nature are pleasing to the eye, and it is very interesting to observe their life. But the real magic begins when you decide to breed them. Fortunately, even a novice aquarist can breed swordtails, because they do it perfectly well on their own.

These fish are viviparous, which means that they give birth to fully formed, lively fry rather than eggs. Your main task is to create suitable conditions for them in time and ensure their safety. Adult fish, including their own mother, may perceive the young as food, so you need to think in advance about how to protect them.

When the fry appear, the most important issue will be feeding them. These tiny creatures need special, very fine food several times a day. How healthy and strong they grow depends directly on the right starter food. Let's take it step by step: from preparing the aquarium to the first weeks of the fry's life.

How to determine the sex of a swordtail

The swordtail is an aquarium fish with clearly expressed sexual dimorphism, meaning that it is easy to distinguish between male and female swordtails by their appearance.

The main difference is that males have a gonopodium, a modification of the anal fin that looks like a groove. Females have a wide, rounded anal fin. Females are also significantly larger than males. Females reach a length of 10-12 cm, while males only reach 7-10 cm.

Males have an elegant, elongated body shape, while females have a rounded body shape. Females have a rounded, large, clearly defined abdomen, through which the eggs are visible. There is a genital spot on the tail. Before pregnancy, it is light in color, but then darkens as the eggs develop.

Males have an elegant and elongated body shape, while females have a rounded body shape.

Possible errors in determining sex

When breeding swordtails at home, despite the clearly manifested sexual dimorphism, it is still possible to make mistakes in determining sex.

What not to do:

• Pay attention to the color of the fish;
• Look only at the sword-like protuberance, which is a modification of the caudal fin, not the anal fin.
• Determine the sex of fry up to 4 months of age, because only after this do their sexual characteristics begin to form clearly.

This species of aquarium fish is prone to a phenomenon known as sex inversion. This means that sometimes a female can fertilize another female, but in this case, the offspring will be weak.

Why else is it important to know the sex?

Swordtails are kept in an aquarium at home. For group keeping, the sex of each individual should be determined. Breeding swordtails involves keeping a flock of five or more individuals.

Breeding swordtails involves keeping a group of five or more individuals.

To avoid fights over females, stick to a ratio of 1:2 or 1:3, meaning there should be fewer males. If there are fewer females than males, it'll cause fights between the males. This will also lead to various injuries in the males.

When breeding pure lines, females and males are kept in separate tanks. They are only placed in the same aquarium for mating, after which they are separated again.

Preparation for breeding

Proper preparation is necessary for breeding swordtails in order to obtain healthy and strong offspring.

Conditions	Characteristics
Optimal age	From 6-8 months and older, some females may begin breeding earlier. However, fish older than 4-5 years should not be paired.
Housing conditions	The water in the aquarium must be clean. Every day, ¼ of the water should be replaced with fresh water. The temperature should be maintained at 25 degrees. This factor during pregnancy affects the sex of the fry. If the temperature is higher, more males will appear, and vice versa.
Diet	The diet should include an abundance of various proteins. Most often, the diet includes cyclops, bloodworms, daphnia, and plant-based foods.

The diet must include an abundance of protein

How swordtails mate

Swordtails are livebearing fish. During mating, the male inserts his gonopodium into the female's abdominal cavity, transferring gametes. These remain in the female's body for a long time, allowing her to give birth several times.

A female can give birth about 4-5 times, even if she is separated from the male after mating. Each time, a large number of fry appear.

Pregnancy

After mating, swordtails enter a period of pregnancy, which must be distinguished by characteristic signs.

How to tell if a female swordtail is pregnant

To determine that a female swordtail is pregnant, pay attention to the following signs:

• Pregnant females have a clearly visible rounded abdomen, with a distinct step-like transition from the abdomen to the head, which appears smaller.
• Such females develop a brood patch located near the anal fin, which darkens and increases in size during pregnancy.
• Their activity level drops, and the fish try to hide.
• Just before giving birth, the shape of the abdominal cavity resembles a rectangle.

Just before giving birth, the shape of the abdominal cavity resembles a rectangle.

How long does pregnancy last

The time during which a pregnant female carries her offspring is not characterized by a specific constant value. It is determined by a number of factors:

• feeding;
• water temperature;
• lighting in the aquarium and some other characteristics.

However, on average, the duration is approximately 40 days, or 4-6 weeks.

The short duration of pregnancy allows for offspring to be produced quite often.

Behavior before giving birth

Experienced breeders know that the behavior of a female before giving birth differs from the usual. It is necessary to know what signs characterize it. If this is not monitored, the birth will take place in the general aquarium, and the young will become prey for other individuals.

Before giving birth, a live-bearing female loses her appetite, hides in algae thickets, and darts around the aquarium, showing signs of restlessness. The behavior of a pregnant female should be closely monitored so as not to miss the moment of birth and to have time to transfer the individual to a separate container.

Before giving birth, the female is moved to a spawning tank. This is a special aquarium of about 10-20 liters, where the newborn fry will be raised.

The female is transferred to a spawning tank before giving birth.

Swordtails are unpretentious and prolific fish that breed easily in a home aquarium. To obtain offspring, it is enough to keep a male and female together in a spacious aquarium with clean water and plants — fry appear 4–6 weeks after mating. They are born immediately mobile and are able to feed on small live food: Artemia nauplii, crushed bloodworms, or special starter food for fry. The main thing is not to overfeed them and to monitor the cleanliness of the water so that the fry grow well and do not die.

Birth of fry

After swordtails reproduce in the aquarium, fry appear. To raise them properly, you need to learn some rules.

Before giving birth, the female is transferred to a spawning tank. Immediately after the young are born, she is returned to her previous tank. This prevents the female from eating her own offspring. After birth, the young usually hide in algae.

However, if the conditions are right, the fry can be left in the general aquarium, but some of them will still die. It is only worth leaving them with adult specimens if there is no way to separate them.

How swordtails give birth

If the female shows signs of pregnancy, she should be transferred to a spawning tank, otherwise the fry will be eaten. Swordtails usually give birth in the morning, and the process usually takes a couple of hours or a couple of days. Swordtails give birth to one fry at a time with intervals.

How many fry do swordtails give birth to?

A female can give birth to several hundred fry at a time. Swordtails can only spawn under favorable conditions.

A female can give birth to several hundred fry at a time.

How to determine the sex of swordtail fry

Until they reach four months of age, swordtail fry are difficult to sex accurately. To determine sex, pay attention to the presence or absence of a gonopodium, which forms at 3-4 months.

The first days of the fry

After birth, swordtail fry are fully formed but not yet fully developed. They are approximately 1 cm long.

The fry are ready to feed on their own immediately after birth.

What to feed swordtail fry

For rapid growth, it is important to provide high-quality food for the fry. Fish should be fed about 4-5 times a day in small portions. After 2 months of development, the fish can be fed three times a day.

The fry should be given:

• rotifers;
• artemia nauplii;
• tubifex worm;
• cyclops;
• dried and ground daphnia.

Fry should be fed dried and ground daphnia.

These types of food can be purchased ready-made at any pet store or made at home. To do this, you will need to set up a separate aquarium for breeding swordtail food.

Before using purchased feed, it must be thoroughly washed and checked for various parasites that can harm newborn fish. Animal-based feed can also be served frozen. However, it is preferable to serve such food live.

It is forbidden to feed sick or dead invertebrates to fry.

The diet should also include plant-based food. This includes special flakes with fiber and algae. Adding spirulina to the food promotes the normal development of fry and the formation of bright colors.

How fast do fry grow?

If you provide appropriate nutrition and conditions in the aquarium, the fry will grow very quickly. After 4-5 months, the individuals will be fully ready for reproduction. For accelerated growth, it is necessary to move them to a separate aquarium and provide a varied diet.

If provided with adequate nutrition and conditions, fry grow very quickly.

Caring for offspring

After the offspring are born, the aquarist must provide appropriate conditions for the normal and timely development of swordtail fry. If the conditions are unsuitable, there is a high probability that all the offspring will die.

Setting up a spawning tank

At first, the fry usually stay in a specially equipped spawning tank. It should be planted with small-leaved plants in which the young fry can hide. There is no need to add substrate to the bottom. A special lamp should be installed above the aquarium, and a heater and aeration system should be installed inside.

When transferring a pregnant female to a spawning tank, it is necessary to add a little water from the aquarium where she lived before. This simple manipulation will prevent the fish from becoming stressed, which could harm the future offspring.

When to transfer

As the fry develop, make sure they have enough space in the aquarium. If the fish are crowded, they will be small in size and may develop various growth and developmental defects.

During the development of the fry, make sure they have enough free space.

As the fry grow, they are sorted and transferred to the main aquarium when they reach the required size. They must grow to a size where they can no longer be eaten by larger and more aggressive neighbors.

It is important to consider the moment when the fry have already switched to adult fish feed. Before that, they should not be transferred to the general aquarium. Most often, this can be done after 3-4 months.

At this time, it is already possible to determine the sex of the newborn fish, which will allow you to form groups correctly for further breeding of swordtails.

If they were born in a community aquarium

If the fish gave birth in an aquarium with adult fish, the fry will become easy prey for other members of the species. In this case, the young fish should be transferred to a special spawning tank as soon as possible.

However, not every aquarist has the opportunity to transfer the young fish, in which case the following should be done:

• Place an abundance of dense plants in the aquarium, both attached to the bottom and floating freely, in which the fry will hide from aggressive neighbors.
• Feed the entire school more often, placing food in a feeder for adult fish and distributing special food for fry on the surface of the water.

The entire school needs to be fed more often

However, this will not help save every fry; part of the school will still be eaten.

As you can see, breeding swordtails is an exciting and quite accessible process. The main thing is to create comfortable conditions for the fish, remove the pregnant female in time, and take care of the safety of the fry after they are born.

The most important thing in the early days is proper feeding. Small live food, such as Artemia nauplii or micro worms, will give the fry the best start for growth. If this is not available, high-quality dry food, ground into a fine powder, will suffice.

Don't forget to keep the breeding tank clean and monitor the stability of the water parameters. If you pay attention to these details, you will soon have a whole school of healthy and active little swordtails frolicking in your aquarium.