Swordtail – Xiphophorus hellerii

Swordtails, known scientifically as Xiphophorus hellerii, are among the most popular aquarium fish for both beginners and experienced aquarists. Attractive colours, interesting behaviour and relatively simple care requirements make them a perfect choice for home tanks. In this article you will learn how to keep swordtails healthy and thriving, which conditions they need, how to breed them, and what equipment will help you create a stable environment. MB Store supports every stage of this adventure by offering quality aquariums and accessories tailored to the needs of livebearers such as swordtails.

Origin, appearance and natural behaviour

The swordtail comes from Central America, where it inhabits streams and rivers with moderate current, dense vegetation and a stable, warm climate. In the wild, these fish live in shoals and constantly patrol the middle and upper areas of the water column. Their name refers to the extension of the male’s caudal fin – a long, narrow “sword” that gives them a very distinctive silhouette. Females are more rounded and lack the extended tail, which makes sexing adults relatively easy.

In aquaristics you will encounter many colour varieties: classic green, red, orange, black, as well as marbled and lyretail forms. Selective breeding has allowed enthusiasts to create patterns that strongly differ from the original wild type. Despite this diversity, all forms retain similar care requirements and characteristic livebearing reproduction. A single well-planned tank can therefore host an impressive, colourful group of swordtails that remain active throughout the day.

Behaviourally, swordtails are generally peaceful but energetic. Males can be territorial, especially in smaller tanks or when too few females are present. They chase each other, display their fins and “fence” with their swords, but serious injuries are rare in well-arranged aquariums. Observing these complex social interactions is one of the greatest pleasures of keeping this species. If you provide enough space and visual barriers, the aggression is dispersed and the fish form a dynamic, visually engaging community.

Tank size and water parameters

Although swordtails are often sold as beginner fish, they should not be kept in very small aquariums. Adults reach about 10–12 cm, and males with long tails appear even larger. A recommended minimum for a small group is 80–100 litres, but more space is always beneficial. Long tanks are better than tall ones, because these active swimmers use primarily horizontal distance. In a sufficiently spacious aquarium they show natural behaviour and the hierarchy among males stabilises more easily.

Water parameters should resemble their native habitats. Swordtails prefer slightly alkaline, moderately hard water. Ideal values are a temperature of 23–27°C, pH 7.0–8.0 and medium hardness. Stable conditions are more important than perfection; sudden fluctuations cause stress and make fish more susceptible to disease. Regular partial water changes, efficient filtration and moderate water movement help maintain quality. MB Store offers reliable heaters, filters and complete aquarium sets that make it easier to create and stabilise these parameters at home.

Proper filtration is a fundamental element of swordtail care. These fish produce a fair amount of waste, especially in heavily stocked community tanks. A filter with biological and mechanical media keeps the water clear and supports beneficial bacteria that convert toxic substances into less harmful ones. It is worth choosing an oversized filter or models with adjustable flow so you can adapt circulation to tank size and livestock. Purchasing proven aquariums and filtration systems from MB Store ensures a safe base for setting up your first or next swordtail project.

Aquascaping and equipment for swordtail tanks

An ideal swordtail aquarium combines free swimming space with densely planted zones. Arrange the middle and front parts more openly, while the back and sides fill with plants and decorations. This layout mirrors natural habitats and provides both shelter and territories. Plants with long leaves, such as Vallisneria or various sword plants, create a wonderful background. Floating plants can softly dim the light and help shy tankmates feel more secure.

Hardscape elements – roots, rocks and branches – serve as important visual barriers. They break up lines of sight, which reduces conflicts between males and allows weaker individuals to avoid constant pursuit. At the same time, they lend the tank a natural character that enriches daily observation. Combine several types of textures, but leave open lanes for swimming. Swordtails often patrol the length of the tank, so do not block the entire midwater zone with heavy décor.

When choosing lighting, aim for moderate intensity that supports plant growth but does not overly stress the fish. Modern LED systems, available at MB Store, allow you to adapt brightness and colour temperature to the style of your aquascape. Efficient filtration and a properly sized heater are equally important. Many ready-made MB Store aquarium sets already contain matched devices, making them an excellent starting point for new aquarists. For more advanced keepers, individual components can be selected to precisely match the needs of a larger or specialised swordtail tank.

Feeding and nutrition

Swordtails are omnivores with a strong tendency to graze on plant material and algae. In nature they consume small invertebrates, larvae, biofilm and bits of vegetation. In the aquarium they willingly accept dry food such as flakes, granules and chips. The basis of the diet should be high-quality products rich in protein and supplemented with plant ingredients. Regular feeding with spirulina-based foods helps maintain good digestion and intensifies colours, especially reds and oranges.

For optimal condition and reproduction, diversify the menu with frozen and live foods. Daphnia, brine shrimp, mosquito larvae or micro-worms provide valuable amino acids and stimulate natural hunting behaviour. At the same time, do not forget about vegetable matter: blanched spinach, zucchini slices or special herbal tablets are excellent supplements. A varied diet supports immunity and reduces the risk of deficiencies that could lead to deformities or weakened growth in juveniles.

Feed swordtails in small portions two to three times a day, ensuring that all individuals, including timid females, have access to food. Overfeeding leads to water pollution and obesity, which shortens lifespan and can predispose to metabolic problems. Use high-quality fish food available at MB Store, paying attention to ingredient lists and recommended portion sizes. Combining diverse feeds with regular observation of body shape and activity will help you maintain a healthy, balanced population.

Social behaviour and suitable tankmates

As social fish, swordtails feel best in groups. A good configuration includes more females than males, for example one male for three or four females. This ratio reduces pressure on individual females, because males are very persistent during courtship. In larger tanks you can keep multiple males, especially if there are numerous hiding places. Observe the group for signs of excessive aggression; fin damage, constant chasing or hiding may signal that you should rearrange the décor or reduce the number of males.

Community aquariums with swordtails can be extremely attractive. Peaceful, similarly sized species make the best companions: platies, mollies, larger tetras, peaceful barbs and many catfish species. Avoid fin-nipping fish and very small nano species that could be stressed by the swordtails’ energy. Also be cautious with slow, long-finned fish, as occasional chasing may occur. The aim is to achieve a harmonious mix where all species occupy their own niches, reducing competition for space and food.

Swordtails occupy the middle and upper parts of the tank, leaving room at the bottom for corydoras or other bottom dwellers. This vertical division of space increases biodiversity and allows you to observe interactions at different levels. With carefully chosen tankmates and appropriate group sizes, the aquarium becomes a dynamic yet stable ecosystem. MB Store provides not only equipment, but also advice on selecting compatible livestock and accessories that support long-term balance in your home freshwater tank.

Breeding swordtails in the home aquarium

Swordtails are livebearers, meaning that females give birth to free-swimming fry instead of laying eggs. Breeding often occurs spontaneously in well-maintained tanks, even without special preparation. After fertilisation, gestation usually lasts about four to six weeks, depending on temperature and individual condition. A pregnant female has a noticeably enlarged belly and a dark gravid spot near the anal fin. As the birth approaches, she may separate herself from the group and become more restless.

If you want to raise a larger number of fry, consider setting up a dedicated breeding or grow-out tank. It does not need to be huge; even 30–50 litres with a sponge filter and dense vegetation can work well. Moving the pregnant female shortly before birth protects newborns from being eaten, as adult swordtails, including the mother, do not show parental care. After giving birth, the female should be gently returned to the main aquarium to regain strength in familiar surroundings.

Fry are relatively large and able to consume powdered dry food, freshly hatched brine shrimp and finely crushed flakes. Frequent, small meals combined with regular water changes ensure rapid, healthy growth. It is important to monitor population density, because swordtails are prolific and can quickly overcrowd a tank. Planning in advance where young fish will go – to other hobbyists, additional aquariums or local shops – is part of responsible breeding. MB Store can supply appropriately sized aquariums, sponge filters and heaters that make managing separate grow-out tanks significantly easier.

Health, lifespan and common problems

With proper care swordtails can live between three and five years, sometimes longer. Their health largely depends on stable water parameters, a varied diet and low stress. Many issues arise from overcrowding, irregular maintenance or introducing new fish without quarantine. Parasites, bacterial infections and fin rot tend to spread quickly in neglected tanks, so early detection and swift action are essential. Daily observation helps you notice subtle changes in behaviour or appearance before they escalate.

Typical warning signs include clamped fins, lethargy, loss of appetite, rapid breathing, white spots or ragged fins. If you observe such symptoms, first test the water for ammonia, nitrites and nitrates. Poor water quality is often the root cause or an important co-factor. Regular partial water changes, gravel vacuuming and filter maintenance prevent toxic build-up. Fish kept in clean, well-oxygenated water with appropriate hardness and pH fall ill far less frequently than those in unstable conditions.

Quarantine for new arrivals is another key practice. A separate 20–40 litre tank equipped with a simple filter and heater allows you to monitor fish for a few weeks before adding them to the main aquarium. This step greatly reduces the risk of introducing pathogens to an established community. MB Store offers compact tanks and necessary accessories that can serve as quarantine or hospital setups. Investing in such infrastructure pays off by protecting your main swordtail population from avoidable disease outbreaks and stress.

Why swordtails and MB Store make a great combination

Keeping swordtails combines aesthetic pleasure with the opportunity to learn about fish behaviour and genetics. Their colourful varieties, easy breeding and visible social interactions make them an engaging subject for everyday observation. At the same time, they are hardy enough to forgive minor mistakes, which makes them ideal for hobbyists who want to move beyond the absolute beginner level. By setting up a well-planned swordtail aquarium, you create a living, dynamic display that remains interesting for years.

MB Store supports this journey by providing high-quality aquariums, filtration systems, heaters, lighting and decorative elements. Whether you plan a modest 80-litre community tank or a more extensive set-up with multiple breeding and grow-out tanks, you can find suitable products and configurations. Combining reliable equipment with good husbandry practices significantly increases your chances of long-term success. Instead of constantly solving technical problems, you can focus on observing your fish and fine-tuning the appearance of your aquatic world.

Thanks to a broad assortment and practical experience, MB Store helps you select components that match your budget and aspirations. Swordtails reward such thoughtful preparation with intense colours, lively behaviour and frequent offspring. If you provide them with stable water conditions, a balanced diet and a well-designed environment, they will quickly become the stars of your aquarium. Over time, you may even decide to experiment with selective breeding, creating your own distinctive lines of these classic livebearers.

FAQ

How many swordtails can I keep in my aquarium?
The number of swordtails depends on tank size and filtration. For a 100-litre aquarium, a good starting group is one male and four to six females. In larger tanks you can add more males, but always maintain more females to spread attention. Observe behaviour and water quality; if you notice stress, aggression or elevated nitrate levels, reduce the population or upgrade to a bigger aquarium.

Can swordtails live with other fish species?
Swordtails usually do well in community tanks with peaceful, similarly sized fish. Good tankmates include platies, mollies, larger tetras, rasboras and many catfish species. Avoid fin-nippers and very small nano fish that could be stressed or outcompeted. When planning community setups, ensure enough space and hiding places so each species can occupy its own zone and minimise conflicts over territory or food.

Do I need a heater and special equipment for swordtails?
Swordtails come from warm regions and require a stable temperature, so a heater is highly recommended in most homes. A reliable filter, proper lighting and a well-fitting lid are also important. While they are hardy fish, unstable temperatures and poor filtration quickly lead to health issues. MB Store offers complete aquarium sets and individual devices that help create a safe, comfortable environment with minimal daily hassle.

How can I tell if my swordtail is pregnant?
A pregnant female swordtail has a noticeably rounded belly and a dark gravid spot near the anal fin. As birth approaches, she may isolate herself, breathe slightly faster and become more nervous. Gestation lasts about four to six weeks. Providing dense plants or a separate breeding tank helps protect newborn fry from being eaten. After giving birth, return the female to the main tank so she can recover.

What should I feed swordtails for best colour and health?
For vivid colours and strong health, offer a varied diet: quality flakes or granules as a base, plus frozen and live foods like brine shrimp or daphnia. Add plant-based components such as spirulina foods or blanched vegetables to support digestion. Feed small portions two or three times a day, avoiding overfeeding. Consistent, diverse nutrition combined with clean water keeps swordtails active, fertile and resistant to disease.