Swordtail Fish – A Complete Guide (Care, Diet, Facts)

Known as a popular community fish that can be widely found in home aquariums as well as the waters from Mexico to Honduras, Swordtail Fish are a species of fish that are easy to care for and can make a great addition to your existing aquarium of fish, or in one of their own.

A peaceful and social fish, these fish will mingle with other passive fish with ease, creating a non-stressed atmosphere.

As they are easy to care for, there are still some precautions to take into consideration, as well as some advice that will help you increase the livelihood of your fish and their habitat.


Species Overview + Typical Behavior

Native to the waters of streams and rivers contained in North and Central America, Swordtail Fish can be found in environments with lots of vegetation, accompanied by other species of fish. Swordtail Fish are social creatures, and enjoy the company of other passive fish.

At first glance, the first thing you may notice on a Swordfish is its caudal fin; the long, ‘sword’-like fin extending out of its back. These are only found on males, so distinguishing between sexes is rather easy.

Due to their popularity in home aquariums, and the demand for them, Swordfish can be found displaying a variety of colors. Natively, they are dark-green colored with a red stripe, but in captivity, they can be found in a range of colors containing red, orange and others.

As common in nature, the females are a bit bigger than males when fully grown, around 6.2 inches. Full sized males can reach up to about 5.5 inches in length.

As mentioned, the natural instinct and general mood of the Swordtail Fish is peaceful, and they are rather easy to care for. If kept with other fish in the same aquarium, be sure to have it only consist of other passive, non-aggressive fish. The presence of aggressive fish can stress your Swordtail Fish out, causing it to hide and display irregular patterns of behavior.

Proper Tank Setup

Swordtail Fish are not very commonly found exploring the ground level of aquariums, and tend to hang around and explore more of the middle to higher levels. For this reason, the substrate you choose to use in the aquarium is not the most important factor.

But, if you wanted to replicate their natural environment as closely as possible, the best choice would be sandy substrates with a finer finish.

Crucial to their way of life and activity cycle, it is important that your tank consists of a considerable amount of plants and vegetation. In addition to exploring and munching on the plants, Swordtail Fish will often hide behind or in between plants when feeling stressed.

There are a variety of plants to choose from, many being easy to care for. These include, but are not limited to;

  • Amazon Sword
  • Vallisneria
  • American Waterweed
  • Java Fern / Moss

Preferring a more alkaline-based water, it is recommended that you keep your aquariums water at a pH of 7.0-8.2. The hardness of the water should be around 12-30 dGH. Within these ranges, your Swordtail Fish will be the most comfortable and active.

Native to tropical waters and temperatures, your Swordtail Fish can thrive in and will be most comfortable in a temperature range of around 70 degrees F – 82 degrees F. Always be sure to maintain and supervise the temperature of your tank, as any drastic changes can affect any fish in your tank, weakening their immune system and making them more susceptible to illness.

A sudden and drastic change in temperature can also result in shock, possibly killing your fish.

For a single Swordtail Fish, it is recommended that you have a space able to contain at least 15 gallons of water. For each additional fish, an extra 5-7 gallons would be needed. This number will vary depending on how many fish you plan to have in your tank, and what kind. Swordtail Fish are small, but are very active and curious, prompting them to swim around often and use up a lot of space.

Male Swordtail Fish can become aggressive toward other males in the presence of females, so be sure to maintain a ratio of around 3 to 4 females to every 1 male, in order to avoid stress and aggressive behavior.

Swordtail Fish are known to be jumpers, so it’s important to keep the top of your aquarium secured to avoid any accidental deaths.

Taking Care of Your Tank

When it comes to your fish livelihood, there is little that is more important than maintaining a healthy, functioning ecosystem within your tank so that your fish can live healthy and stress-free.

Taking care of your aquarium is not the most daunting job, but it does require that you do regular maintenance and check-ups on the quality of water, and other signs of potential danger.

Before any new water goes in to your tank, it is crucial that the water is conditioned with a dechlorinating agent, in addition to the use of a biological aquarium supplement. If the water is not treated, many properties within the water foreign to fish and home aquariums will invade the space and cause health and safety issues.

Taking into consideration the temperature range recommended for your one species of fish  / mixed aquarium, never allow for drastic changes in temperature to take place. As mentioned, a drastic change in temperature can throw off your fish’s immune system, and make them susceptible to many health issues. Find an average range that works well for your fish, and do your best to avoid allowing sudden changes to happen.

Buy a pH test kit and regularly check the acidity value of your aquariums water. The general, recommended range of pH for a lot of aquarium fish is around 6.8-8.2, but always be sure to know exactly what range should be used for your fish. Check daily for quick and sudden changes in pH, as great changes in a single day can cause your fish to become sick.

If you notice an abundance of algae growing within your tank, that means that there is less oxygen available for your fish to breathe in. Algae sucks up oxygen, and an excess can leave your fish struggling to breathe properly. Having an algae scrubber / algae magnet is great to quickly get rid of that gradual build up you will inevitably notice at one point or another.

It is recommended that you replace at least a portion of your tanks water every month, perhaps around 25%. This replacement will work to keep your tank water clean, as well as keeping levels of nitrate / nitrite in check.

Whether you have a single species aquarium, or a mixed one, be sure to ask your local specialist what they believe the necessary parameters for nitrate, nitrite or ammonia might be.

Feeding Your Swordtail Fish

Lucky for you and them, Swordtail Fish are not very picky eaters, and will eat most anything that you try to feed them.

In order to provide a wide range of nutrients, feeding them commercially prepared flake-foods will work very beneficially towards their health, providing them with almost everything they need.

In addition to the flake-foods, feeding your fish frozen foods such as brine shrimp, bloodworms and tubifex can provide them with healthy proteins and minerals. These frozen foods are especially important at a young age, when they need a lot of protein intake.

Your Swordtail Fish can benefit greatly through the consumption of vegetation, whether it be through munching on the plants contained in their aquarium or through vegetational supplements that you are giving them during feeding time. Vegetation consumption can help your fish’s digestive process.

Due to the benefits of vegetation in their life, it is recommended to supply their aquarium with considerate vegetation, as well as feeding them vegetational supplements during feeding time.

Even though they do not need tons of food at a time, it is recommended to feed your Swordtail Fish about 2-3 times a day, perhaps sticking to a regular schedule if possible.

Tank Mates, And Which Ones May Be Best

As mentioned, Swordtail Fish are a very social type of fish, and certainly enjoy the company of other passive fish. Coupled with the right species of fish, Swordtail Fish can be a great addition to your aquarium, helping to promote a stress free and lively tank!

As the popularity of home aquariums has grown over the years, so have the amount and availability of many types of fish, and there are many passive species to choose from.

When looking for fish to share a home with your Swordtail Fish, your choices can include, but are not limited to;

Each of these fish are known to be passive, and rarely display signs of aggression. Keeping a considerate ratio of more females to males will reduce the likelihood of males displaying signs of aggression.

Mixing in aggressive fish with your Swordtail Fish will likely result in them being stressed out and end up hiding, or even eaten by the aggressive fish. For their safety and longevity, be sure to only mix them in with passive fish species.

Breeding Swordtail Fish

Being a livebearer species, female Swordtail Fish deliver the eggs after full development. Due to this, they can breed often and efficiently, and start doing so at around three months of age.

If you are trying to promote your Swordtail Fish to breed, there are a few factors that you could implement to try and get them to do so. Simply enough, feeding them a diet with a range of nutrients, such as those provided in flake foods and vegetation, will help give them the energy and desire to breed.

In addition to this, keeping the tank clean can be representative of how they feel, so keeping your aquarium clean and sustainable will help to boost their instincts to breed. A clean tank, as well as periodically increasing the temperature to around 80 degrees F, can help promote breeding.

When your Swordtail Fish is pregnant, you will notice a dark spot on her lower abdomen appearing. In about 4-6 weeks, the fry will be fully developed in will be delivered.

Adult Swordtail Fish often eat many of their fry after they are born, so it is important that you separate the fry from the adults to reduce as many casualties as possible. There are breeding traps that can help you do this. Vegetation in the tank can help hide them, but it is likely that many will be eaten if left to grow in the same aquarium as the adults.

Keeping the fry separated from adults during the growing process if the best idea, and you will only need a tank that holds around 15 gallons to let the fry comfortably grow.

After the fry have grown and are big enough to not be seen as a meal, slowly introduce them back to your tank, and watch for signs of aggression and adjustments. When introducing the grown fry back into the aquarium, be sure to consider the recommended female to male ratio of around 4:1, in order to reduce the likelihood of aggression.

It is important that young and growing Swordtail Fish receive a lot of protein, and this can be consumed through frozen foods mentioned earlier such as brine shrimp and bloodworms.

Now You Know!

After reading through this guide in its entirety, you should now feel more than confident to start your new Swordtail Fish aquarium, or to introduce Swordtails to your existing aquarium! As a passive and social species, Swordtail Fish are a relatively low-maintenance fish, and do not require tons of care and attention in order to live happily.

Be sure to supervise your tanks water parameters, feed them often, and watch them explore! Swordtail Fish are a fun and curious species that will prove to be a valuable addition to your pet family and home aquarium!

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