Swordtail Stats
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.
Housing
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
Feeding
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.
Breeding
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.
How old do red velvet female swordfish have to be to become pregnant???
They can start breeding as early as 3-4 months, though they usually breed a little bit later than that.
I have a 800 gallon outdoor tank in a tropical climate with a lot of plants. There are hundreds of guppies and sail fin Mollies. Will the swordtail eat the fry of the other fish if all are well fed? Thanks!!
Virtually all fish will eat fry if given a chance. When they are well-fed, they tend to eat less fry, which is the best you can really hope for. Swordtails aren’t notorious for eating fry, and with lots of plants and a tank that large, you shouldn’t lose too many of them.
Thank you very much about the information
Hello All, I have 6 feet fishtank and I Had 2 male and one female Swordtail, the femail dide in few days after and just the male left, I decided not to buy any more female. the strange thing start after 2 months, I saw baby Sowrdtail in my fishtank, they becom more and more and now I have more then 20 sowrdtail, all of the are male, no femeil!! the mail start atrarackting othere mail, I never see them pregnant, no sign of big belly!!! but every other day i see one or tow baby sowrdtail.
can someone explain how is it possible???
I’ve heard of them changing sex (though I haven’t read any studies about whether this real), but without another one in the tank, I have no idea what could be happening. I’m stumped on this one.
It’s not changing sex, no male fish is a female now. They all have the male look long tail and funny is they do the same kind of attraction which they usually do to a female new the do it to a male. They always do the attraction and dancing to the male who accept it and they fight to other make who coming close. I think I’ve got gay fish in my tank
have you ever heard some of live bearer fish male can save sperm ? and that is real, you can see swordtail fry in your tank because in some cases the male when they’re pregnant the black point is small and you can not recognize them.
I have a problem that my male swordtail tries to mate with my ryukin goldfish, when I have two female swordtails, one being pregnant upon purchase, but no fry were alive when I noticed she had them , I have plants but I looked and there were none left.
I wish I could help you with that one – that must be an interesting sight to see. But there’s not much you can do to dissuade a passionate swordtail. Probably the only thing to do in a situation like this is to separate the fish.
As for the plants, the goldfish probably at them all. They are murder in plants in an aquarium.
Hey Kevin , sounds like the female had laid her eggs before she died and after a while you began to see the fry with only the 2 male swordfish in the tank.
I don’t think that they lay ages????
what is the fish physiology ?
Sorry, but what do you mean by that? Do you mean their adaptions?
Harry swardtales are live bearing fish no eggs
How long after they are born should you keep them in the nreeder net? We just bought ours and she started having babies so we put her in a breeder net? How lone before we should take out the mother and how long should the babies stay in the net?
It all depends on the type of fish you’re keeping them with. The key thing you want to avoid is them being small enough to fit into another fish’s mouth. So if you keep them with larger cichlids, they need to be kept safe until they’re at least the size of a dime (1/4 inch/1 cm). But if they’re just with other swordtails, you can add them when they’re quite small – especially if you have a planted tank.
My swordtail had babies a week ago and now she looks like she is about to have more babies is that possible
There’s no doubt she’s most likely pregnant again, but it should a few more weeks. Unless of course she’s very bloated. Does it look like her scales are sticking out?
How often can female get pregnant
They pretty well stay permanently pregnant. They store sperm in themselves, and they’ll often be pregnant a very short time after they give birth.
I have two females and a male and a young male the males never fight that chase each other and the two females aren’t prengnet at all for alit leats a day and I had fry but there was 1 left and it disappeared.the male is Mary gold and flame tip females Mary gold.
Pls help me!!!!! Thank u
The fry are probably being eaten by the parents. Do you have any live plants? Java moss is especially good for fry to hide in. Also, floating plants work quite well.
How many production can get from 29gallon tank?hiw many pairs can put on this tank?
I have many small swordtail babies that are all female… what dictates the sex of offspring?
My understanding is that studies have shown that temperatures at the high or low end of their preferred range produce more males, while a more balanced temperature produces around the same number of males and females. However, this is just generic fish information, and I’ve never read a specific study on swordtail fish male-to-female sex ratios, so I’m just assuming it still applies to these fish.
Is that okay that the fry is together with the guppies and has no fake plants but have some floating plants to eat
You may lose some fry, but I think most would survive with guppies – especially with floating plants to hide among.
I had one male and two female swordtails about 4 days after giving birth all of the adults died what happened and how do I keep them alive?
I had a clean tank, clean filter, good bacteria and 1:3 swordfish. But the male was in stress for sometime and died yesterday. But now I see another female is also in stress. I wonder what’s wrong. 🙁
Have you checked the water quality recently? Usually, it comes down to a problem with the water quality (many pet stores like Petsmart will test your water for free). If it’s not the water, then it’s likely illness. Did the male show any signs of illness before he passed? Any bloating? Did the poop look normally or stringy?
Let me know and then we can go from there.
how long does a female stay pregnant before giving babys
Roughly 1 month
I need to know as I have2 females pregnant 1 is about a week and the other is about 2 week into pregancy
So, my swordtail just had her second “nest”. The first one resulted in 28 (now) juveniles, which are 6 weeks old at the time of writing.
at the moment, the second nest is in the same tank as the 6 weeks old juveniles, but what’s the best moment to move the juveniles to the large 180 gallon tank?
I’ll separate males from the females as soon as I can determine their sex.
It really depends what’s in the main tank. While it’s not very scientific, I always try to move the fry when they’re larger than any fish mouth in the main tank. If they’re too large to eat, then they should usually be fine. Assuming there aren’t any overly aggressive species in the tank of course.
How many red swordtails can you keep in an aquarium before they get over crowded. I have a 180 litre tank