Fish Keeping and Aquascaping Blog

February 3, 2010

Keeping and Breeding The Swordtail Fish

Filed under: Uncategorized — Prabhu M @ 4:57 pm
Tags: , , , , ,

Hello. This is my post on keeping and breeding the swordtail fish. If you are new to the swordtail fish or if you are looking for more info on breeding and caring for the swordtail fish, then you have hit the right page.  This post will go over the profile and characteristics of the sword tail, and look at it’s care and requirements. I will also discuss about breeding them and raising their fry ( i.e. baby fish ).

The Swordtail fish ( scientific name : Xiphophorus helleri ) is one of the popular aquarium fish. The name Swordtail is derived due to the unique sword-like tail seen in adult males. These fish are very active in the aquarium, hardy and easy to keep and come in a variety of colour , hence making them a popular choice for newbie’s in Aquarium keeping.

Swordtail Male

Now let’s look at some of the common profile specification of the Swordtail :

a) Common Name : Swordtail fish
b) Scientific name : Xiphophorus helleri
c) Origin : Commonly found in the flowing waters of Central America
d) Preferred Water Temperature : 22C – 28C
e) Preferred pH of water : 7-9
f) Max Size : Can grow upto 4 inches in the aquarium
g) Compatible Tank Mates : Generally Peaceful. Hence suited for a community aquarium with non-aggressive tankmates.
h) Breeding Class : Livebearers ( i.e Swordtails do not lay eggs, but give birth to live young ones )

Swordtails found in the wild are generally green ( olive green ) in colour with the sword being yellow with black or brown borders. Cross Breeding in captivity by fish farms and hobbyist has given many strains of Swordtails with varying colours like red, red velvet, red wag tail, marigold, pineapple colour, black, etc . Different strains like Lyretail a.k.a. ‘Double Sword’ and ‘high fin’ are also available, giving the aquarist numerous options to choose from.

Swordtails are very active and lively in the aquarium and unlike other fish, move around all levels of the aquarium ( i.e. They can be seen moving in the bottom , middle and upper layers of the tank ). Hence you need to house them in an aquarium which has adequate swimming space. Higher activity in the aquarium leads to higher oxygen comsumption by the fish, and hence they need a well aerated aquarium . This is also seen from the fact that they are usually found in fast flowing streams of Central America, which are rich in dissolved oxygen.
Swordtails are good jumpers and could jump out of the tank when they are disturbed, stressed or scared. Hence it is advisable to keep your swordtails in a tank which has a cover ( hood ) and keep the tank in an area with minimal noise and disturbance. Keeping the tank in an area with minimal noise and disturbance is necessary to have stress free and healthy fish, irrespective of the kind of fish you house in your aquarium. Another trait I have noticed in my years of swordtail keeping is that they seldom jump in a planted tank. They get a sense of security in a well planted ( read densely planted ) tank, and hence are not disturbed or stress easily in a planted tank. I have lost quite a few fish due to their jumping habit whenever I forgot to put the cover on my breeding and grow-out tanks. On the contrary, I have seldom seen them jump in my display tank, which is heavily planted.

Sexing of the fish : Swordtails are sexually dimorphic, i.e. you can identify the sex of the swordtail fish by their external appearence. The male of the species develops a distinct ‘Sword’ in it tail fin as it matures, while the females do not. Also, the mature males show a distinct male sex organ near the anal fin, called the ‘Gonopodium’. It is through this gonopodium that the males deposit their sperms into the females during mating. The above two features are a sure shot way to distinguish a male swordtail from a female swordtail. Other differences are in their relative size, while the males are thinner and look elongated, the females are more round and grow a little larger and longer than the males.

Now, why am I talking about sexing the fish so early in the post. Shouldn’t it come under the breeding section ?! The reason for this is simple. Swordtail males tend to become territorial as they mature. When there are fewer females in the tank, the males tend to fight with each other for these females ( or rather for the ‘right’ to mate with them 🙂  ). Hence it is advisable to purchase more females than males when you visit your pet store. I know that this would mean fewer fancy sword’s since the females do not develop a sword, but that’s the least you can do for a peaceful aquarium . The generally accepted practice is to have 3 females for every male swordtail in an aquarium. Swordtail breeders generally have 5 females  for every male ( so as to keep the male always  busy 🙂 )

To be continued…….



  1. Hello sir,
    I’m a new member to IAH… I’m very much impressed with your tank setup….

    Comment by james — April 14, 2010 @ 2:04 pm | Reply

  2. Thats a wonderful post! I’m so delighted you thought to share it.

    Comment by MicidEgy7 — May 12, 2010 @ 9:19 pm | Reply

  3. i bought 6 swordtail fish & dunno distinguish the male n female..only 1 survive..thank for ur info..i think i need to buy the female ..

    Comment by Mr.Homosapiensz — July 24, 2010 @ 7:17 am | Reply

  4. i have 2×1.15x1feet tank..
    want to start 4x2x2feet Planted.
    Can u tell me can i supplie CO2 continue DAY – NIGHT or i should Shut Down CO2 at Night.???
    Reply me

    Comment by Jitendra Patel — September 22, 2011 @ 1:22 am | Reply

    • Both options are used by hobbyist’s. The only difference is that you will have to refill your CO2 cylinder more frequently if you keep it one even during the night.
      I do not see a need to keep them on during the night.

      Comment by Prabhu M — September 22, 2011 @ 10:59 am | Reply

  5. Hi sir, i am sandeep from kerala(india).i bought 3 lyretail swordtail fish(1 male and 2 female).i came to know that it is very difficult to breed them,especially the male will not breed with the it true?what should i do to breed my red eye swordtail male will breed with the female lyretail.pls help me. My mail id- ( soon.

    Comment by sandeep — January 19, 2012 @ 2:27 am | Reply

    • Sandeep,
      Breeding Lyretail Swordfish with a Lyretail male is very difficult. This is because his gonopudium is unable to perform the normal function of penetrating the female.
      The usual way that breeders use to breed Lyretail Swordfish is to use a Lyretail Female with a Normal Male. The offspring’s would be a mix of Normal and Lyretail Swordfish.

      Comment by Prabhu M — January 19, 2012 @ 8:31 am | Reply

  6. Hey, I had 3 females and 1 male swordtail and they all died within a week. I had the ph and temperature right, I also had a filtration system. I also remembered to put in water conditioner and had the water quality at its best. I think the reason they died was because i didnt put salt in it. Does the swordtails need salt? if not, can you find the reason why they died?

    Comment by fifi — February 29, 2012 @ 9:43 am | Reply

    • Hi Fifi,
      Fishes do not need salt in their water, unless they are sick and you are trying to regulate their osmotic balance.
      I suspect that your tank was new and was not cycled properly. You might want to read more about tank cycling and Nitrogen cycle before you add new fish into a newly setup tank.


      Comment by Prabhu M — February 29, 2012 @ 10:17 am | Reply

  7. i want to ask, if they breed will my other fish eat the babies?? i have got 5 endlers guppys, 2 pearl gouramis, 6 rummy nose tetras and some corrys

    Comment by sarah — October 11, 2012 @ 2:48 pm | Reply

  8. I’ve got a question.
    When I was buying my lyretail swords six months ago, the lady who bagged then for me told me that the females happen to turn to males as they age. No one believed me when I told them about it, so i was wondering if that’s true, because if not, I will need to have a talk with the lady who bagged the fish. I don’t know if she just wanted to make me more interested in the fish or what, but I’d like some answers.

    Comment by Kristina — November 23, 2012 @ 1:02 am | Reply

    • Kristina,
      The males in swordtail fishes are born males, and they do not change their sexes from females to males.
      Some of the males are late to change their appearance ( i.e. late in showing off their sword or gonopodium ) and hence they appear like females until then.
      Hence this myth that females change their sex to males in their later life.

      Comment by Prabhu M — November 24, 2012 @ 7:42 am | Reply

  9. Morning.

    I’m getting swordfish for my son today. Just want to know how many fish can I put in a 30 liter tank.

    Comment by Luzette — November 8, 2013 @ 1:08 pm | Reply

    • Hi,
      30L tank is a pretty small tank. I would not keep more than 4-5 sword-tails in them.
      You have to account for their grown-up size, not just the size they were when you bought them.
      4-5 should be the max in a 30L tank.

      Comment by Prabhu M — November 8, 2013 @ 1:51 pm | Reply

      • Thanks for replying. I went and bought a 60l tank and got 10 swordtail fishes. The water stays milky the whole time. What can it be. I also have plants and 2 filters in. Please can you tell me why tank water stay milky. Thanks

        Comment by Luzette — November 9, 2013 @ 8:01 pm

  10. I want to breed my sword tail fish,.. Please kindly give a tips for succesful breeding.. I have a janitor fish in my aquariun too…will it a risk to my swordtail….?

    Comment by Rockybert — March 20, 2014 @ 5:55 pm | Reply

  11. excellent source of info here man! thanks for the knowledge.

    Comment by The FishScape Dojo — August 14, 2014 @ 3:01 pm | Reply

  12. Hi I had a female swordfish jump out my tank which has a hood/cover on – would anyone be able to comment as to how this happened, poor thing didnt survive, but I cant understand how it jumped out. Tks

    Comment by Terry — October 29, 2014 @ 1:59 pm | Reply

  13. I just got a pineapple swordfish and two bala sharks just the other day and the swordtail just unexpectedly gave birth and I didn’t realize until I little bit ago. I am new at this and I have no idea on what to do so PLEASE HELP ME. all the stores are closed as well and im not sure what to feed them or help them survive the night.

    Comment by colbey — February 24, 2015 @ 9:36 am | Reply

    • Hi Colbey,
      As a homemade food you can feed them hard boiled egg yolk. Separate the egg yolk from an hard boiled egg, gently scrub the yolk with your fingers/spoon and then dip your finger/spoon into the water. The Baby Fish/Fry’s would like this. But note that the water gets dirty with this pretty quickly. So you may need to change the water every day or two. After a few days you can take them towards finely crushed flakes.

      Comment by Prabhu M — February 24, 2015 @ 5:05 pm | Reply

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