Minimum Tank Size: 29 Gallons (132 Litres)
Care Level: Moderately Easy
Water Conditions: 7-8pH and Moderately Hard to Hard
Temperature: 72-82 °F (21-28 °C)
Maximum Size: 6 Inches (15 cm)
The swordtail (Xiphophous hellerii) is a small fresh water fish, native to Central and North America. It’s native range stretches from Honduras in the south, to Central Mexico in the north, but they can now be found on nearly every continent, thanks to aquarium escapes and wild releases.
While swordtails prefer fast moving waters with dense vegetation, they can also be found in numerous other habitats, ranging from small ponds to slow moving drainage ditches. Because of their diverse habitats, they can adjust to a wide range of conditions in captivity, and will do well in most water conditions.
It’s important for anyone considering purchasing swordtails to know that they grow far larger than any of the other commonly available liver bearers. It’s not uncommon for a male swordtail to reach more than 6 inches (15 cm) in length and the females aren’t much smaller. Most females will reach about 5 1/2 inches (14cm) in length – so obviously you will need to provide larger tank for swordtails than you would for guppies or platies.
Swordtails are also relatively long lived for a live bearer fish, and it’s not unusual for a well cared for swordtail to see its 5th birthday, and some are reported to have lived even longer. With that being said, you can expect a normal swordtail to live between 3-5 years.
Since swordtails are a relatively large tropical fish, they should never be considered as a candidate for the all too common 10 gallon tank (45 litres) that many people start out with. While it’s not hard to find people who claim that they will do well in a 10 gallon tank, they really need something larger to prevent stunted growth and potential illness.
The minimum recommended aquarium size for swordtails is 29 gallons (132 litres) – but that’s only if you don’t plan on breeding them. However, that’s easier said than done and like any other live bearer fish, any tank containing both males and females will quickly fill up with fry. So if you have the budget for it, you might want to start with something larger than 29 gallons.
Although it’s not an absolute requirement, you should try and provide live plants for your swordtails. A heavily planted aquarium closely mimics their natural habitat, and also provides cover and shade for the fish. While fake plants will also work, they don’t offer the dual benefits of improving water quality and oxgenating the water that live plants provide.
When choosing a filter for swordtails, bigger is usually better. If you can afford it, you should always try to over-filter your tank, and swordtails will enjoy the current that an over-filtered tank brings with it. HOB (hang-on-back) filters are usually the best choice, as they are both economical and efficient.
I would strongly recommend choosing an Aquaclear Power Filter for a swordtail tank. This filter combines excellent filtration with a durable design, and it will keep your tank sparkling clear for years to come. You can also read the Aquarium Tidings Aquaclear Filter Review here.
In the wild, swordtails are omnivores, and feed on a variety of invertebrates, insects, plant matter and algae. This diet should be reproduced as closely as possible in the home aquarium and can be accomplished through feeding a variety of foods.
The main portion of their diet should consist of a high quality flake food, and it should be supplements with blanched vegetables and live or frozen foods. One of the best foods on the market is Hikari Micro Pellets and swordtail fish love this food.
This is by no means an exhaustive list, but some vegetables that are hungrily accepted are zucchini medallions, cucumber medallions, shelled peas and broccoli. All vegetables should be blanched in boiling water first and allowed to cool before being added to the aquarium.
The best live foods to feed to swordtails are daphina, blackworms, bloodworms, brine shrimp and mosquito larvae (illegal to culture in some areas). Their taste in frozen foods are pretty similar and they can be fed frozen daphnia, blackworms, brine shrimp and bloodworms.
Like most other live bearers, swordtails will normally breed on their own without any intervention from their owners. There is a common joke that to get swordtails to breed, just add water – and this isn’t far from the truth.
With that being said, it’s important to ensure that you have enough females in the tank with any male swordtails. Males will often harass the females with relentless mating attempts, and if there aren’t enough females, any females in the tank can quickly become stressed – which can lead to illness.
Also, unless you have a very large aquarium, it’s best not to keep too many males together. It’s not uncommon for them to fight over the females, and the best male to female ratio in a smaller tank usually 1:3 or even 1:4.
Once a female swordtail has been impregnated, she will begin to swell with the quickly growing fry. You can tell if a female is pregnant both by a massive increase in belly size, and a dark gravid spot near her anal fin. The gravid spot is caused by the fry’s eyes pressing against the females scales.
Even if you don’t keep the female with males, most female swordtails will be pregnant when you first get them. If they have been kept around males for any length of time, they will usually have enough sperm stored inside of them for several pregnancies. So always be prepared for fry when you purchase female swordtails that are kept with males at the petstore.
If you plan on keeping the fry, you should take some extra steps to ensure that they survive. If the parents are going to be kept with fry, then a heavily planted tank is a must. The best plants to choose are dense or bushy plants, and Java moss in particular provides an excellent refuge for new born fry.
Alternatively, you can remove all of the adult fish from the aquarium after the fry have been born, which will protect them from all the hungry adults. This also reduces the amount of waste in the water which is further beneficial to the newborn fry.
Some people put pregnant females in a breeding net, but I find that increases their stress levels and you can end up with early births. The best method is to remove the parents or provide adequate plants.
Once the fry are born, they will accept most of the commercially available fry foods, but their mouths are also large enough that they can accept powdered flake food. If you want to raise the heathiest possible fry, you should consider feeding them live foods, and microworms and baby brine shrimp are both excellent choices.