The Aquarium Guide

Swordtail Fish Care Guide

Swordtail fish (Xiphophorous hellerii) are a very popular community aquarium fish. Their popularity stems from their ease of care and peaceful nature. They have quite unique types of fins with a great variety of colors, making them commonly referred to as Red swordtails or Green swordtails. Today, they are bred to achieve various colors and, as a result, great deals of different types exist.

Swordtail Fish

In the wild, swordtails usually have olive green bodies with a red stripe that stretches along the body. Their natural habitat is in Central America and North America, where they were discovered in 1848. Swordtail fish are average size freshwater species; males are typically slightly smaller than females (6.3 inches) and they reach 5.5 inches maximum. They live in groups, but are not a schooling fish. One of the things that make them so popular is their hardiness, as they can survive in very diverse environments.

Whether you plan to keep them as a single aquarium species or in a community aquarium, you should know their general needs.


Swordtail fish are average-size fish; they don’t need very much space due to their size, but given they are very active, they greatly benefit from having enough space to swim around. The minimum tank size for one adult swordtail fish should be at least 15-gallons. However, if you plan to add other fish for good company, plan to house them in at least a 29-gallon aquarium. The best male to female ratio is one male and three or four females. In this way, males won’t overly harass the females, as harassment will be evenly distributed. Swordtails are great jumpers so consider covering your aquarium in order to prevent possible suicide attempts.

Water parameters

Swordtail fish are sturdy tropical fish that can tolerate a wide range of water temperatures. They should do fine in any water temperature between 65- 82⁰Fahrenheit. Even though they are adaptable and quite durable, avoid sudden and violent temperature drops in temperature, as this can harm your fish and make their immune system vulnerable.

Swordtail prefer very hard water from 12–30 dGH and an ideal water pH anywhere between 7.0 and 8.4. In general, they prefer moderately alkaline, hard water.

Always take care that your water is properly filtrated. If you set your filtration system right, the water parameters will stay strong. Always keep track of water parameters so you can react and prevent possible complications. Your fish will then happily thrive and live to full potential.


Swordtail fish will accept a wide variety of foods. You can give them quality flake food or live foods like bloodworms, daphnia, brine shrimp, mosquito larvae, or fruit flies, as they will eat virtually anything.

Swordtail fish eat a lot of algae and other vegetation in their natural habitat. Don’t neglect their need for proper herbivorous food. Make sure to give them an ideal mix of protein and vegetation in order to perfectly satisfy their exact diet needs.

Swordtail Fish

Tank mates

Swordtail fish are a peaceful and active species. They are very social and enjoy good company, especially when housed with other swordtails or similar passive species. The swordtail fish can make a great companion in similar cousins, such as platies, mollies, or angelfish. Peaceful types of corydoras are also great as their companions. Some larger types of tetras can be great, too, but keep them in schools of five or more to prevent possible harassment.

Male swordtail fish are almost always aggressive towards other males of the same species. If your tank isn’t huge, you should definitely opt to keep only one male along with two or three females in one tank.


As livebearers, the swordtail fish are great at breeding efficiently and very quickly, without any intervention from the aquarist. Once a swordtail female has been impregnated, you should clearly see a huge belly with a dark gravid spot near the anal fin.

Once the fry are born, you should take some protective measures in order to keep them alive otherwise they will be consumed by their parents or other tank mates. You can do this either by adding more plants that will serve as hiding spots for young fry or by physically removing adults (or fry for that matter) from the tank.

The latter is much more efficient, as only some of the young will survive if they are not separated from the adults. When the fry become large enough not to be viewed as food by adults, gently introduce them to your tank.

6 thoughts on “Swordtail Fish Care Guide

  1. Well now that I have 2 sword tail fish, I have been learning a lot about them, however, how well would it work if I were to have say like 5 or 6 female sword tail fish with the 2 male swordtail fish that I have already?

  2. The common and best ratio is 1 male to 3 or 4 female fish so 2 males with 6 female fish would be Judy fine if you take care of them all right.

  3. I have two male swordfish in one tank with 7 neon tetras as well as 2 mollies and 4 guppies. Is it alright to do this?

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