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FAQs on the Swordtail Compatibility

Related Articles: Swordtails & Poeciliids: Guppies, Platies, Swordtails, Mollies by Neale Monks, Livebearing Fishes by Bob Fenner,

Related FAQs: Swordtails 1, Swordtails 2, Swordtail Identification, Swordtail Behavior, Swordtail Selection, Swordtail Systems, Swordtail Feeding, Swordtail Disease, Swordtail Reproduction, Livebearers, Guppies, Platies, Mollies,

Fin nipping swordtails vs. flame tail tetras; incomp.      5/23/14
Hi my name is Ashley I'm recently new to keeping fish we have a I believe 55 gallon tank that a company's Glo fish (9) swordtails (3) about 10-20 flame tetras and a couple of other fish I forget there names we have about fourth fish in our tank. All small but we recently got two out of the three sword tails making is with three. And I have noticed then nipping at the tetras fins until they die why is this and what should I do please help I love my little tetras
- Ashleu
<You'll need to separate the Swords from the others... either by having another tank, or returning, giving away one or the other.
Bob Fenner>
Re: Fin nipping swordtails vs. flame tail tetras     5/24/14

Thank you so much we did move all three to are 15 gallon tank and everything seems to be going smoothly so far.... Fingers crossed all the other fish in the big tank seem to be more spread out since the swordtails are out of it
<Ah, good. Thank you for this follow-up. BobF>
Re: Fin nipping swordtails vs. flame tail tetras     5/25/14

Okay I have another question. Now that I know all the fish names. We have2 tiger barbs
<Groups of 6 or more, otherwise tend to be nippy, and even in groups shouldn't be trusted with long-finned fish.>
3 scissor tails
<Usually fine. Again, a schooling species: keep six or more.>
4flame tail tetras
<Aphyocharax erythrurus is not especially widely kept, but other Aphyocharax species tend to be a little nippy with long-finned fish.>
10 neon tetras
<Usually harmless.>
4platys 3red1yellow
<Usually harmless.>
8glofish 4orange 4pink
<Danios; these are not usually nippy, but they can get aggressive if bored.
Need numbers and swimming room.>
2yellow sucker fish they are long
<What are these? Gyrinocheilus aymonieri? If so, these are MUCH too large for 30 gallons when mature. Get to about 25, 30 cm in length, and become extremely territorial and sometimes downright nasty when mature. One in a 55 gallon tank might work. Useless algae eaters as adults.>
1 sting Rey sucker fish
<Do you mean some sort of Hillstream Loach such as Beaufortia kweichowensis? Not really a community fish.>
5 algae eaters
<Again, what are these? Otocinclus would be fine in this sort of tank and in these sorts of numbers. But five Ancistrus would be a real squeeze, while five Pterygoplichthys wouldn't even fit once mature! The common Algae Eater catfish sold to aquarists who don't do research are Pterygoplichthys; these get to up to 45 cm/18 inches in length and should be kept singly in very large tanks only.>
3sword tails in the other tank.
<Males are aggressive.>
Anyway my question is are tank is actually 30 gallons instead of what I originally told you. And we still have are neon tetras being killed (I originally thought they were flame tails sorry) out of all the fish do you see any thing wrong compatibility wise with these fish. Besides the sword tails they are in the other tank.
<At first glance this seems an insane collection of fish. Perhaps you can clear up some of the uncertainties for me. But you have too many species not kept in sufficient numbers (barbs, tetras) on the one hand, but also too many of other fish that simply won't work in the long term (various "algae eaters").>
Thank you
<As Bob would say, "keep reading". You're building up problems here, and seem to have fallen into the old "pick and mix" trap of choosing one of everything from the shop without checking to see if they will actually work out in your aquarium. Lots at WWM to help you plan a better aquarium *once* you take back some of these species. Cheers, Neale.>
Re: Fin nipping swordtails vs. flame tail tetras

Thank you again and yes I'm starting to do my research about all these fish n down grading to only certain fish
<You may find these pages a useful place to start reading:
And do also read some of our replies to other freshwater stocking
questions, here:
Cheers, Neale.>

Angelfish and swordtails     8/8/13
I finally upgraded to a 75 gallon tank and have three adult angelfish. They get along, but that is luck with that number. They live in hard water and the temp is in the late 70's. Would a few female swordtails be a bad idea?
<Not a bad idea. Should be a very nice addition here... Do like hard water, can tolerate the stated water temp.; and there's enough room for them to get away from the angels...>
I think they may be fin nippers or really aggressive. I read about someone who kept angels with swordtails and they said the male swordtails went after a small angelfish and killed it. Are they that bad? Thank you
<Not bad. Do search, read on WWM re the compatibility of both. Bob Fenner>

Territorial Female Swordfish     5/13/13
I have a 26 gallon tank with 8 neon tetras, 2 black neon tetras, 2 male guppies, a male molly, a Pleco, and a female swordfish.  My temperature and water quality are great (I bring samples to my pet store for testing regularly, and I monitor my thermometer).
<Ah, but the values mean more than the word "great" does. For example, Neons and Black Neons prefer soft, slightly acidic water, whereas Guppies and Swordtails prefer hard water with a pH above 7. Mollies may even do better in slightly saline conditions. In other words, what's "great" for Guppies will be "barely tolerable" for Neons, and vice versa.>
The female swordtail was given to me yesterday by a friend who was unable to care for her any longer.  She was living with neon tetras in her last home.  I introduced a small amount of my tank's water to hers and set her bag in my tank to adjust for a while.  After introducing her to the tank, she seemed happy and quickly claimed one corner of my tank as her own.  I noticed last night and this morning that she continues to chase my molly away every time he comes near her corner.
<Not unusual.>
She is fine with the guppies and tetras coming close, only chases the molly.
 Do I need to worry about her becoming aggressive?
<She won't get any worse than she is now.>
I have yet to see her nip at anyone, but I love my molly and I hate to see him stressed. What can I do?
<Not much. Swordtails are naturally a bit boisterous, as are Mollies, so in a relatively small aquarium, a bit of friction is more than possible.
Swordtails rarely do much harm, but bear in mind they come from fast-flowing streams whereas Mollies prefer still water habitats, so Swordtails are much better (stronger, faster) swimmers. Needless to say while both species need a fair amount of space (26 gallons is only just enough for them) the Swordtail will want to rush about much of the time, so prefers a long rather than deep tank, and may even be a bit jumpy (literally as well as figuratively) in small aquaria.>
Sent from my iPhone
<Sent from my computer. Cheers, Neale.>

Indescribable... mixing Swordtails w/ neotropical cichlids...      4/23/13
Dear Crew,
    I'm in a bind. It is my fault.
<This is when we reflect upon "lessons learned.">
I attempted to add three swordtails to my 50 gallon Jack Dempsey/ Red Devil tank today.
<Your Dempsey would like to express gratitude for the meal.>
Literally 30 minutes ago.
Both the Jack and the Devil IMMEDIATELY ate one of  the three swords WHOLE.
Both the male and one of the two females.
<Not surprising.  Anything that will fit into the Dempsey's mouth is a goner. Consider it a demonstration of how an invasive species can wipe out native fish.>
 The male sword was two inches without his gonopodium
<Unless the gonopodium was freakishly long, it doesn't impact the length of the fish.>
and the female the same size. My male Jack is around six inches and the Devil is around four or five inches. I honestly expected some bullying until the swords settled in and the two cichlids accepted their new tankmates.
<Uh-uh. Nope. Aggressive and territorial and hungry cichlids will take out a 2-inch livebearer.>
I was also prepared for the idea that if bullying ensued I would remove the swords and return them. Boy, was I wrong. My
question is will the two cichlids survive their meal; or, is this the "last supper?"
<Unless the livebearers were ill or carrying parasites, the cichlids should be fine. Do watch for symptoms over the next six weeks.>
I'm devastated at the loss of the swords and I am returning the last female to my LFS tomorrow. Will she survive the night or, should I go ahead and remove her to a plastic bin with aeration for the evening?
<If you leave her in the tank with the cichlids, you will likely not have anything to return by morning.>
My LFS is already closed for the night and I have no available qt at the moment as I have it occupied with three T. ocellocaudus, so this is my only option.
The last sword is currently alive and exploring with no more aggression towards her, for the time being.
<Well, the cichlids have full stomachs for the time being.>
Thanks for all the help and experience the WWM crew affords our hobby,
<This is one reason why experienced aquarists tend to migrate toward keeping species tanks. A tough lesson to learn, but one you won't likely forget. - Rick>
Re Indescribable... mixing Swordtails w/ neotropical cichlids...      4/23/13
Thank you, Rick.
As predicted when the lights went out she disappeared. <Not surprising.>
This experience has indeed been a lesson learned. On another note, I have a fantastic rapport with my LFS and they allow me to qt livestock for a month at a time and still return anytime within the month.
I had the swords for about three weeks and at this point there is no sign of illness. This attempted community was somewhat of an experiment( my first with livebearers and CA cichlids ).
<It is possible to keep some livebearers and cichlids together, but you must be very selective.  For example, I have sailfin mollies housed with Julidochromis dickfeldi (Tanganyikan cichlid), which isn't an optimal solution but it works.  Key here are three factors. One, the fish are comparable sizes so no adults get eaten, second, the Julies protect their young and the mollies mass produce young, so they can live in the same tank if it's large enough without catastrophic losses of fry, and finally, there is a rocky area for the cichlid and planted area for the mollies. But it still isn't an optimal arrangement.>
My LFS loves my fish so when my cichlids breed they always take the whole stock off my hands ( i.e. Convicts, Jack Dempseys, Red Devils etc.).
<Useful to have a store like that, for sure.>
Anyway, could I attempt this again, with any foreshadowable degree of success, but instead of the Jack and the Devil use T. meeki? Being Eartheaters, albeit anecdotally aggressive and certainly territorial, but not piscivorous(?) could this have a greater chance of success?
<You can try as long as the fish are comparable sizes.  Might work, might not work, and could be somewhat dependent upon individual dispositions of the fish involved.>
 I'm not aiming for a true biotope just something CA community-ish with both colorful and interesting cichlids and medium to small tankmates( i.e. swordtails, since I prefer the dimorphism of them as compared to larger livebearers).
<Study the fishes involved and look for ways it won't work. If you think the odds are in favor of survival, go ahead and try it, but be ready to separate species if necessary.  As I said, I didn't know if julies and mollies would work together but they seem to get along provided the mollies stay clear of the breeding cave. If they get too close, they are chased off, but pursuit doesn't go past that.>
Again, thank you for the wealth of knowledge your site offers our wonderful
<Very welcome. - Rick>

Male Guppy harassing male swordtail.- 10/18/12
Hi all,
<Hi April>
In my 20g long tank I have 2 male orange tailed guppies, 1 male neon swordtail, 1 Opaline gourami -Trichogaster trichopterus, and 2 sunburst Mickey mouse platy - Xiphophorus maculatus. One of my guppies will not leave the swordtail alone. The swordtail has shown no aggression what-so-ever to any other fish in the tank. Is this deviated sexual attention since I lack female guppies?
<Maybe. Could be trying to establish dominance also. What gender are the platies? I'm guessing male, as well.>
It has gone on for two weeks now. I bought a breeding net and have isolated the guppy in it for 4 days. I tried letting him back out and immediately back to the sword, not giving him a break at all. So back in the breeder net he went. I waited another day and tried again, with the same outcome.
<Instinct perhaps.>
I'm fond of both fish, however, I feel one may have to be traded in to solve this problem? I prefer not to add females since I do not yet want to raise fry, but I will if that is the best option. I don't have a separate tank for fry and feel bad knowing they'd most likely get eaten. Would adding more male guppies help in this situation, to possibly make it where one male can not establish a territory?
<Livebearers in general are not territorial.>
Or will my poor swordfish have lots of males chasing him? The other guppy will follow suit if the one is chasing, but while that one is in the net, the remaining one does not mess with the sword much. Only occasionally if they pass each other. I notice such an increase in the swordtail's activity with the guppy isolated. If more males are an option, how many? If not,
would 6 females deter these two guppies from pestering my sword?
<Almost certainly, but watch you don't overcrowd your tank.>
I would then be learning how to raise fry I suppose.
<The guppies handle most of it themselves. They are born large enough to eat crushed flake and they will graze algae.>
The only other tank I have has two 3.5" Yellow Belly Slider turtles in it, so I fear the guppy would become dinner if I moved him to it.
<Quite likely. If you make plenty of hiding places for the sword to escape the attention of the guppy then you may be able to leave the population alone.  Otherwise, if you don't want to return the guppies it would be best to have them in their own tank.>
Thank you for any insight!
<Welcome - Rick>
Re: Male Guppy harassing male swordtail.- 10/18/12

Thank you for your quick reply.
You are correct, the platies are both males. I guess establishing dominance would have been a better choice for my wording, rather than establishing territory. Is it possible the guppy will find his dominance and leave the swordtail alone?
<Depends if the sword accepts the guppy as dominant. Considering his activity is less when the guppy is around, I'd guess he has accepted a subdominant role, but the guppy may be overzealous on enforcement.>
Would adding more male guppies help, or only females?
<Maybe. It would give the dominant guppy more fish to keep in line.>
I had originally planned on a few more males, but worried that could make the problem worse so have held off.
<All you can do is try it and see what happens. I'd start with another two maybe. Don't forget to quarantine first.>
I'd love to have males and females and ultimately fry, just know my tank space is limited so not sure what I'd do with tons of guppies!
<Sell them, keep them, trade them, auction them, give them away, feed them to cichlids. The options will largely depend on pedigree.>
I will look tomorrow for some Indian fern to add hiding places. I have quite a few hiding places already, but will see if more does the trick.
<Livebearers love plants, so more won't hurt a thing.>
<Regards, Rick>

Swordtails, comp. w/ Platies    8/8/11
I have a 46 gallon bowfront. I was wondering would it be ok to keep a few female swordtails in there if they were sharing the tank with two male platies, or are swordtails just too aggressive?? Thank you!!!
<These livebearers will likely mix (and interbreed) fine here, given the size and shape of this volume. Start w/ "not-too-large" swords. Bob Fenner>
Re: Swordtails; stkg./sel.: size and comp.     8/8/11

Are there actually smaller species of swordtails?
<Mmm, not really... there are ones that have been stunted, and others that have had fab care, frequent feeding and water changes... that can be HUGE though. There are other Swordtail spp., but these are rarely sold/seen in the trade>
I was in a LFS the other day and I saw some female swordtails that were HUGE. If they were hollow, you could fit eight platies inside them, they were that big.
<Yes; have seen six inch plus specimens>
I am assuming that males would be too aggressive to keep with two male platies in a 46 gallon? I heard they are terrors. Thank you!!
<Domesticated Swords aren't that mean. BobF>

Guppy vs. Sword...    5/30/11
I am worried about my male Swordtail fish and male Guppy also. They do not seem to be getting along. My Guppy whom has been in the tank the least amount of time seems to be harassing my Swordtail fish whom was one of the first additions to my tank. Most recently my Swordtail fish has taken to hiding in the ornamental castle that I have in my tank. This is causing me much concern as this has never happened before. The castle is a new ornament I have place in the tank, even so I have had many ornaments that my Swordtail could have hidden in before but chose not to. My question is it natural behaviour for the swordtails to hide as mine has never done so before?
<Yes; is natural to hide if being harassed>
Also is it safe to keep my male Guppy and male swordtail together in the tank.
<Maybe not... How large is this system?>
Everything that I have read seems to suggest that they are compatible tank mates?
<Not always, no. But generally it's the larger species, the Sword/Xiphophorus that is more aggressive>
If this is so then why is this behaviour happening between my guppy and swordtail?
<Likely territorial, perhaps deviated sexual drive>
I believe that my swordtail may now be hiding due to harassment from the guppy. As well as my swordtail fish hiding he has taken to just "sitting" at the bottom of the tank. The only other fish that I have that tend to do this are the clown loaches. This is normal behaviour for them I believe but I do not believe that this is normal behaviour for the swordtails. I do not know if this is also being done by my swordtail due to the harassment from my guppy. I would be very great full <grateful> if you were able to help me understand what is going on in my fish tank. To give you some background information on my tank set up, I have nine fish in total 2 clown loaches, 1 algae-eater (I do not what kind)
<Do check on this... some get too big, agonistic>
1 Betta, 1 Angelfish, 1 Molly, 1 Goldfish
<Should be elsewhere>
(I have no clue as to what this fish is, as it was a present. It looks like a spotted goldfish), 1 Male Guppy and 1 Male Swordtail. My fish are all happy and healthy from what I can see. They are kept in a 20 Gallon water tank with the water temperature set at between 72-74 almost constantly (At times it does go below 72 but in a couple of hours will return to 72). I have a water filter constantly on and also a ultra-violet light constantly on.
Any help would be very much appreciated as I want to care for my fish as best as I can.
Thank you
Ella Kuhn
<Do try putting the male guppy in a floating plastic colander (or breeding trap if you have one) in the tank for a few days. Such "time outs" often re-set the social dynamic. Bob Fenner
Re: Sword/Gup comp.  6/6/2011
Thank you for you prompted response. I did as advice and purchased a breeding net and place my male guppy within it. This has leaded me to see what was really going on. The reason my guppy was harassing my swordtail was because my swordtail fish is sick. He has been getting progressively worse.
PLEASE HELP!! I noticed that when the guppy was in the breading net not only was the guppy harassing him but also other fish. So I have placed my swordtail in the breeding net to stop this from happening. His symptoms of sickness are, lying on the bottom of the tank and rapid breeding. His colour and skin/scales all look the same as before. Recently I changed a lot of the water could this be the cause?
<Perhaps, but what about the other fishes, livestock?>
All other fish are fine. I am very worried and wanted to do all I can for my fish PLEASE HELP! I have had him for 18 months and am very attached to him.
<Read here: http://wetwebmedia.com/FWSubWebIndex/sworddisfaqs.htm
and the linked files above. BobF>

Battle for food   1/31/11
I have a 20g tank with 4 Swordtails and 4 Green Cory Catfish. I'm feeding them micro wafers that float for a bit and then sink, so the Swordtails knock the wafers down to the catfish. In addition, I'm feeding the catfish Sera Vipachips that sink to the bottom. Problem is, the Swordtails also really like the Vipachips, and it ends up being a battle between the Swordtails and the catfish -- of course, the Swordtails end up eating most of it. Can you maybe suggest a way I can ensure that only the catfish get the Vipachips?
<Easy, this one. Feed the catfish at night! When the lights are out, provide sufficient food for your Corydoras. Do this 3-4 times per week, and you should find they're just fine. Corydoras are nocturnal by nature, despite being day-active in aquaria, and happily feed at night. And no, they won't hide away during the day just because they're being fed at night. Do also remember to keep the tank quite cool, 22-24 C is ideal for both Swordtails and Corydoras aeneus, otherwise their metabolism will be much higher than it needs to be, and that'll place extra demands on their diet as well as shortening their lifespan.
Cheers, Neale.>

Suggested tankmates for swordtails  1/5/11
Hello WWM Crew,
<Hello Ivan,>
I'm looking to stock my 20g (long) tank with a variety of fish. Currently, I'm research swordtails, but cannot find a definitive list of compatible fish. After doing a search, I know swordtails should not be with another kind of livebearer.
<They are indeed quite aggressive and also need cool, fast flowing conditions.>
Thus, my questions are:
1) What types of fish are compatible with swordtails? I'd prefer not to worry about the hassle of keeping track of different types of fish foods, so types of fish that have a similar diet and similar feeding style (e.g., timid, or voracious).
<Really, it's a question of picking species that enjoy relatively cool (22-24 C/72-75 F) conditions with water currents upwards of 6-8 times the volume of the tank in turnover per hour. Good choices including medium to large Corydoras catfish including Bronze and Peppered Corydoras; Bristlenose Plecs, Ancistrus spp.; some of the cooler water cichlids including Blue Acaras; and most of the Danios including all the popular ones such as Zebra and Giant Danios. Avoid fish that are easily harassed by Swordtails, and conversely, avoid species likely to nip at the long swords of the male Swordtails. So while barbs can be good choices, the nippier ones like Tiger Barbs are best avoided.>
2) How many fish can comfortably live in a 20g tank?
<Male Swordtails are aggressive, so in a 20 gallon tank you won't keep more than a single male. I'd recommend one male and 2-3 females, together with, perhaps, a group of 4-5 Corydoras catfish and a single Bristlenose Plec.
Assuming this tank has a good filter and plenty of oxygen, you shouldn't have any problems with this collection.>
3) What types of shelter do I need to provide my swordtails? Also, are there essential useful "decorations" I need in my tank?
<Swordtails are surface-swimming, open water fish, and apart from floating plants that provide shelter to fry, they don't really need other sorts of ornaments.>
Thanks for your help!
<Cheers, Neale.>
Re: Suggested tankmates for swordtails  1/5/11

Hi Neale,
Thanks for your prompt response. You mention a couple times that swordtails live in cooler waters, but I keep reading on the internet that they live between 72-82 F water,
<They do not. Swordtails inhabit cool, fast-flowing albeit relatively lowland streams. While they can live in warmer water, they will be shorter lived, more disease-prone, and in the case of males, more likely to be aggressive. A large number of fish come from relatively cool water: Corydoras, Platies, Neons and Danios, to name just a few, and keeping them far too warm is a major reason some of these are seen as "delicate" or "difficult to keep" by beginners.>
even in a link that was suggested by one of your crewmates
<Perhaps. But do instead look at a trustworthy book such as Baensch's Aquarium Atlas or any one of many books about Livebearers. You'll see that they all clearly state that 25 F/77 F is the absolute top-end of happy Swordtails and Platies.>
I have a Tetra Whisper EX300 filter, does this "turn enough water" to keep swordtails comfortable?
<The Tetra Whisper EX-30 has a turnover of 160 gallons/hour. For a 20 gallon tank, that's a turnover of 8 times, since 20 goes into 160 eight times. Yes, that should be ample. I'm not a huge fan of hang-on-the-back filters for a variety of reasons, but they can work well, and this filter is moderately well regarded. Because Swordtails are "jumpers" any holes at the back of the tank will be a threat, which is one reason why I prefer in-tank canister filters for small aquarium rather than these hang-on-the-back types.>
Furthermore, regarding your list of fish, are they fairly easy to keep? I'm a beginner, so I don't want to avoid higher upkeep species.
<Yes, the ones I recommended were all good, reliable fish that will do well in the moderately hard to hard, basic water Swordtails must have (Swordtails will quickly die in soft water).>
<Cheers, Neale.>
Re: Suggested tankmates for swordtails  1/17/11

Hi Neale,
So I stocked my tank today with 4 swordtails (3 female, 1 male) and 4 green Cory catfish. They've been in the tank now for over 4 hours, and I've been noticing some aggressive behavior from one of the female swordtails. The aggressive female swordtail has white shades and is a "brick" varietal (at least that's what the fish guy told me). I chose her because of her red and white color. She doesn't seem to be overly aggressive, but will nip at the male and the other females. I'm not sure if it's because of her size or her being a different species of swordtail than the others. What should I do? One of the smaller females swims to the other side of the tank whenever the red/white swordtail approaches.
<It's absolutely normal for female as well as male Swordtails to be somewhat aggressive. The best workaround is to add more females if you can.
Do be sure you haven't got males that are "late bloomers", a common problem with very young specimens 3-4 cm long. Otherwise, adding floating plants or at least choosing plants with leaves that reach the top, like giant Vallisneria, can help to provide shelter. Eventually a pecking order becomes established. So long as no-one gets seriously damaged, don't worry too much. Cheers, Neale.>
Re: Suggested tankmates for swordtails   1/18/11

Thanks for your reply Neale. I'll definitely look into creating some shelter for the female Swordtails. I have another question. Now that it seems like they've finally settled into the tank, the aggressive female has
lost her aggressive edge, and the male seems to be taking a liking to her.
This is evidenced by his incessant pursuit of her around the tank. Feeling kind of sorry for her, because I'm sure it must be quite annoying, is there a way I can tell if she is becoming overly stressed by the male's
<Not really, but so long as the females outnumber the males substantially, i.e., at least 2:1, you should be okay. Floating plants make a huge difference, and adding more females will help a good deal too.>
Also, is it normal for males to develop "favorites"?
<Yes, in the sense that they will try to mate with the females that seem (to them) more likely to produce offspring.>
<Cheers, Neale.>
Re: Suggested tankmates for swordtails

Hi Neale,
I did as you suggested, but the Swordtails still find the food... Not sure what I should do now.
<If you feed the catfish when the lights are out and the room is dark, the Swordtails will be unable to feed. This should work just fine. Cheers, Neale.>
Re: Suggested tankmates for swordtails  3/1/11
Hi Neale,
After doing my water change today, I noticed my fishies had babies! There are two small fry in the tank, and I'm not sure how to proceed. Is there anything I need to do now?
<Swordtails will eat their babies given a chance. Use a breeding trap to isolate the fry for about 3 weeks. In the very short term, something like a net weighted down with gravel will work just fine until you can get a breeding trap. Feed the fry very finely ground flake food and they'll be fine.>
<Good luck! Neale.>

Swordtails and good tank mates 08/06/10
Hello. I am Fairly new at this.
I got a 55 gallon tank back in November with some Cichlids and have lost all but one of the original fish.
<Right, I see. Well, cichlids are bad fish to begin with. They're sensitive to nitrite and ammonia, which means they rarely survive the cycling process. Plus, those cichlids inaccurately referred to as "African cichlids" -- usually cichlids from Lake Malawi in East Africa -- may look colourful but they're also incredibly aggressive, and creating balanced, long-term communities takes a great deal of forethought.>
I have never had a fish tank before this time and my friends gave it to me.
I am looking at selling the last cichlid that I have and am wanting to replace it with some fish that will go good with the sword-tails that another friend gave me. after reading the literature that I could find on your website I was set on getting some guppies, but read further along and found that you don't recommend putting two different live bearers together.
<Generally this is true. Plus, Swordtails come from cool, fast-flowing water, whereas Guppies come from warm, still water. So there's no ecological overlap. Male Swordtails are also very, very aggressive.>
So with this contradiction in what I read I am interested in what you would recommend.
<Not a contradiction. If you went to a zoo, you'd see lions, polar bears and raccoons. They're all in the zoo, but they all need different things. Likewise in a tropical fish shop: just because they're all for sale in the same building doesn't mean you can throw them all into the same tank. Often retailers give good advice, but sometimes they don't, and the generic chain store ones tend to be pretty hopeless. Read a book first. Then go shopping.>
I have lost maybe one female sword-tail along with two cichlids over the last month. I did a complete tank clean and then checked the water conditions and everything seemed to be with in normal after the last cichlid died and that was a week and a half ago. the two cichlids I was not sure what killed them, however the first one I now died because the tank got to hot for two long.
<Hmm perhaps, but you're not giving me any data to work with. Let's be clear about what Swordtails need. Firstly, they're stream-dwelling fish, so you're after a cool temperature, 22-24 C/72-75 F. You also need to create a nice flow of water, so plenty of water current is essential. Water chemistry must be hard and basic, 10-25 degrees dH, pH 7.5. That means you mustn't use soft water, especially not water from a domestic water softener. If you have "liquid rock" out of the tap that furs up kettles and other appliances, it's probably ideal! Since Swordtails come from clean, clear water it's essential you have excellent water quality: 0 ammonia and 0 nitrite.>
I need to treat for my Pleco because he is not looking good, due to having to treat Ick in the tank a couple of weeks ago, but I have to go to the store for that and will have that done with in a week and then I am going to be looking into getting the other fish. but I want something that will go good with my sword-tails and give my tank some extra color.
<Do make sure you're keeping the fish you already have properly. I'm not sure you are. Adding more fish within 3 months of the last death or disease is VERY STUPID. Wait for things to settle down. Be sure you have the knack of things. Do a pH and hardness test, and then e-mail me back the results. I'd be happy to recommend you some suitable fish to keep with Swordtails once I know that. Cheers, Neale.>

Swordtail... comp.   12/17/08 I have a 30 Gal. tank I have 5 guppies, 2 Swordtail male/female,1 Betta, 6 neon, and 2 orange fish that i don't know the name of <Shouldn't buy fish you don't know anything about.> My female swordtail is very mean <Xiphophorus helleri can be an aggressive species. Best not mixed with other livebearers.> I've lost 2 guppies and i think it's her <Certainly possible. Does depend on the "orange fish" though -- could be something aggressive, predatory, fin-nippy.> she attacks everyone but the Betta and the Neons what should i do flush her? <Are you winding me up? What makes you think throwing a fish down the lavatory is sensible let alone not cruel? Unwanted fish can usually be returned to an aquarium store; sometimes you'll even get credit.> thanks Dale <Cheers, Neale.>

Re: Swordtail, comp.    12/17/08 Sorry was not serious about the flush thing the orange fish are Platies If i take the female swordtail back to the aquarium store how will the male act? will he be ok thanks Dale <Swordtails are aggressive. Remove the dominant (bullying) fish, and the next one down the pecking order will become the new dominant fish (the new bully). Swordtails are best not combined with platies or guppies. Cheers, Neale.>

Swordtails, sys., comp.  8/21/08 Hello, I am not new to keeping fish but I have a few questions about the swordtail, the HiFin Lyretail Swordtail in particular. First, I have a 5 gallon Minibow freshwater fish tank, and it has a in tank whisper filter plus a 15 watt light bulb which keeps the tank's Temp. at about 74-78 degrees, I have only one fish in the tank at the moment, it is a half-moon male Betta, and I wanted to get two swordtails, a male and a female, I was told by a good friend who keeps the swordtails that this would be fine as long as I didn't purchase anymore fish after that, is this true? And Is all of this correct Information that i have received? Also, if my male Betta has been living in this tank for a while now, and is healthy and active, couldnt the swordtails have the same luck? Aren't they both hardy fish and aren't they both tropical fish as well? So shouldnt they coexist together and be able to live in about the same water conditions also? Sorry for the questions, I just really need to know this from some one who knows their stuff!! Lastly, If I don't want the swordtails to breed, should I just get two females, or will the male and the female get on with their life and forget about each other? Thank you so much for your time, P.S. I did read about the girl who was keeping the swordtails in a 1.5 gallon fish tank, and I can only fit a 5 gallon fish tank in my apartment so is this okay? Thanks and have a good time, sincerely, Mason. p.s.s I haven't changed my email since I was 16, I am currently 18 so this should explain the kid part of the email address! Talk to You soon! <Hello Mason, this is Merritt here today to answer your questions. Well, first of all a 5 gallon tank is just not big enough for swordtails, sorry but you can still keep other interesting fish in a 5 gallon. Also, just purchasing a male and a female would not be good, due to the male being aggressive to the female, it would be better to have 2 - 3 females per male. Another aspect is no, the male and female would not ignore each other, the male would pester the female to mate and then you would have fry to deal with. If you got females you would have to get more than two so a pecking order could be established. Both swordtails and Bettas are hardy fish and can easily be kept together if the tank space allows. Have a great day! Merritt A.>

Male Swordtail Terror  6/26/08 Hello Neale and all WWM Crew. Happy Summer to you. <And to you> This is a question on a male swordtail terrorizing the other two in a 125 gallon tank. The end string below summarizes our fish quantity, but recap is 50 fish; community of platys, swords, mollis, Corys. There are 7-8 assorted female swords. There are 3 males; a medium pineapple, a small black (mature, and a large red 'standard LFS' male. All have been in the tank 6 months to a year. The tank has corner pumps, many fake rocks, plastic grass, etc to hide in. Early on the very large red male was boss and would harass the black one only, who has never attained great size. This stopped. All was calm. Now the very large red is no longer the kingpin male. Though not the largest, the pineapple has begun to really harass, chase, and bite the black and the red. <Strange> Both are becoming skinny, show fin loss, and hide in corners. They can't get to food without being chased the length of the tank. They are not diseased in any way. With 7 females, we thought we were ok; decided to let nature take its course over the last two weeks. But we couldn't stand it, the pineapple is downright being a brute. Today we isolated the pineapple in a large plastic colander in the 125 tank. <Good move> Here are what we feel are our options: 1. Buy more females and hope for the best in the 125 tank. 2. Move the pineapple to a 10 gallon empty fry tank that is operating, along with two females. Hope he wears himself out and the other two recover and fatten up in the 125 tank. 3. Move the red and black male swords to the fry tank along with 4 females to fatten up. 4. Do nothing and hope for the best. (We feel the two harassed swords will die of starvation if we do this.) 5. Hang the pineapple from a yardarm in front of the other fish as a lesson at high noon. <Heeee! Hang 'em high!> Please tell what you think and elaborate as to the +/- of each option. Many thanks, Rosemary and Don <I would go with #1... and possibly try changing the food. Do look into supplanting what you use with Spectrum pellets... sometimes nutritional deficiency can be a large player in affecting fish behavior. I have found this food to be excellent nutritionally, very palatable (to the fishes!), and a calming influence. Cheers, Bob Fenner>

Re: Male Swordtail Terror/Food, Ratio Males to Females  6/27/08 Mr. Fenner, <Rose and Don> Many thanks for your helpful reply. Our pineapple sword remains in solitary on bread and water pending purchase of more female swords. <Good> Missed asking the question of what ratio of males to females might solve our problem. If 2.33 to 1 is not working (7 Females and 3 males), how many females total would be appropriate for 3 male swordtails in our 125 gallon tank with the current animosity? <"The more the merrier"... at least three to one... Am now humming a modified Beach Boys tune...> We feed twice daily. Always daily Wardly Algae Tablets (Corys and the rubber lips), and alternate Tetra Tropical Flakes with shrimp pellets or blood worms. We never personally thought much of the shrimp pellets, too messy. How does that sound for balance and nutrition? <I'd add some more with greens, or greens themselves...> Anything there a waste of time? We will immediately add in the Spectrum Community Pellets to the mix when we get to the LFS> <Is a great product... as you and your aquatic charges will find> Thanks again and cheers, Rosemary and Don <And to you, BobF>

Re: Male Swordtail Terror/Food, Ratio Males to Females Update - 7/1/08 Hello WWM gang, our problem remains. <Really?> Please see the string below. We made a thorough count and had 8 female swords. The black male died of stress/malnutrition while the pineapple male was in the cage, so after 5 days in the cage we let the pineapple male out. The LFS had zero quality swords this week so we declined to buy. We thought we were in the clear with the 4:1 female to male ratio (8:2 in our tank now). Would add that all 3 males and several females had been in our tank for close to a year. The pineapple male sword hid for a half day after we let him out to play, then began to harass the larger remaining red male sword relentlessly (the red hides behind power filters, more nipped fins and really skinny). <Dang!> We increased feed to 3 times a day to fatten up the male red sword, ensure he could get to food. Added fresh peas to the feed with the spectrum pellets, flakes, algae pellets. After two days of terror, we again put the pineapple male in the cage. The red sword is now totally normal, in the open, and eating well with the pineapple male locked up. <Good> Our other fish count is 7 platys, 9 guppies, 10 Corys, 1 Pleco, and 8 mollies. We are close to our normal imposed limit on fish (50) for 125 gallons. We have good water and can add more female swords if you think it best still. <I am considering suggesting trading in the one male, isolating it permanently or suggesting destroying it> Question is, if 8 females: 2 males does not divert attention of the male pineapple from the red male sword, will 10:2 or 12:2 be better? <Too likely not> What should we do? Should we add a bigger male sword and hope to change some dynamic in the tank? Should we let the pineapple out, let him kill the red one, get it over with, and have 8 females and the 1 pineapple male? <This IS likely what I'd do> We have not had this extreme behavior before, so we are at a loss. Any thoughts appreciated. Cheers, Rosemary and Don <Have seen this rogue behavior a few times... even in humans... BobF>

Re: Male Swordtail Terror/Food, Ratio Males to Females Update - 7/2/08 Many thanks, sir. <Certainly welcome> We favor letting the pineapple out and accept what happens as you suggest. <I see> Our reasons are these: In our area, pineapples are difficult to find, reds are dime a dozen; the red may die anyway given the stress; and the dynamics may change and the pineapple may gravitate toward a female. <Mmm> Strange to us (is it to you?) that for all this aggressive behavior, we have not seen the pineapple express any interest what so ever in nuzzling up to females since we got him a year ago. <Interesting... as a reality and observation... Am given to wonder here. Perhaps this really isn't a "real" male... the genetics/expression of sex and traits, behavior in poeciliids is a bit more complex than humans, companion animals that most people are more familiar with... Perhaps we should "chat" this up a bit> We appreciate your most helpful site. Spent 5 hours last night just reading FAQ's on different subjects, feeding, chemistry, and breeding. Wonderful service to aquarium owners that you have going. Sincerely, Don (and Rose) <Ahh! A pleasure to share. BobF>

Hello! I have a few questions about swordtails! Beh., comp., repro.  07/01/07 Dear Crew at WetWebMedia Hello, my name is Oksana. I have two swordtails, a male and female, and a 1 1/2 gallon tank. (Yes, I know, terrible, but my parents won't let me get a bigger one.) Bob, the male, has been living a few months in my possession, seems very healthy. Betty, (The female, I just got her today, June 30) seems healthy too. Before Betty, we've had male swordtails, and Bob, being the dominant one, has always shown a little aggression toward the smaller and weaker ones, and unfortunately, they perished. So anyway, Bob was left alone. The problem is, is that Betty is pregnant. We got her pregnant already from the fish store, and Bob keeps nipping at her. Not full class "bites" just nips. She chases him away of course, but I keep wondering if that's normal swordtail behavior. I have read most of your pages in breeding swordtails, but do you have any extra advice? The local Petshop has already to take in the young fry when they're a few months old, but I have a question on that too. How fast do fry mature? I have seaweed in my tank, a filter, and a hiding place, (Yes, I wonder how they all fit and the fish still have swimming room...) so I don't think I need to take the female out when she gives birth. Any other tips on what to do will be fully appreciated. Thanks very much, Oksana <Greetings. Yes, 1.5 gallons is far too small for swordtails. A 20 gallon tank would be my recommendation for fishes as large and active as these. Males are aggressive, and in small tanks it is safest to keep just one male plus 2-3 females. Females do get harassed by males. There's nothing you can do to prevent this in a tank as small as yours. In a bigger tank, you can rely on plants and rocks to give the female security. But in a small tank, she has nowhere to hide. Long term, the male will likely kill any fry that appear as well. Do not, under any circumstances, place the female in a breeding trap or breeding net. Swordtails are too big for these, and get stressed. Worse case, they die, but more usually spend all their time thrashing about trying to escape. As you know, swordtails are very fast and extremely good at jumping. The ideal when breeding livebearers is to place the female into another tank where she can deliver her fry safely. Good luck! Neale>

My swordtails have been harassing my goldfish! Well, the two aren't compatible species, in many senses...    1/10/07 I have a 15 gallon tank with two 2 inch long female fantails, three swordtails, and an albino Pleco. <The Pleco will soon outgrow that tank, as it can reach over a foot in length! Perhaps more problematic is that swordtails are tropical fish and goldfish are cooler water fish...the two aren't compatible. You need to have two separate environments; one cool for the goldfish, and one warm for the tropicals.  Do read here for basic info. on the two very different types of fish you've got: http://badmanstropicalfish.com/profiles/profile27.html http://www.geocities.com/shtinkythefish/qgold.htm > I have a male swordtail which is about two inches long (underdeveloped tail included) and two females which barely make an inch and a half, and lately I've been noticing the swordtails will nip and sometimes chase my goldfish. <This is yet another problem of housing the two species together...> I read on the internet that swordtails and goldfish don't tend to generally mix well... <Mostly because each has very different environmental requirements!> ...but I was wondering if this will maybe lead to a fatality on the goldfishes part. <It could. And, depending upon what conditions this tank is kept at (pH, temp., etc.), the swords could also become fatalities. Bottom line: you need to research any fish purchase prior to buying it. Had you done so, you would have quickly seen these two types of fish do not belong together.  Here's a very nice by Bob Fenner on setting up a proper goldfish tank - http://www.wetwebmedia.com/FWSubWebIndex/gldfshsystems.htm -  and I highly recommend a book entitled "A Simple Guide to the Freshwater Aquarium" by David E. Boruchowitz for basic info. on all sorts of tropical fish, including swordtails. Also, do read here for livebearer species info: http://www.wetwebmedia.com/FWSubWebIndex/poeciliids.htm > The nips have never (that I've seen) punctured through the scales and their tails are practically intact but I was wondering if this was maybe psychologically harmful to my goldfish, as silly as it sounds. <It doesn't sound silly at all...in fact, constant harassment can lead to a compromised immune system, along with physiological damage, etc. You need to separate the goldfish from the swordtails for a variety of reasons, as cited above. Best regards, Jorie> Goldfish and swordtail compatibility?  6/20/06 Hi again Jorie <Lise> Sorry for bothering you a lot. <It's OK - I'm here to help.> My girlfriend's grandmother has gold fish and I asked her she wanted sword tails after they got big she ask if swordtails go with gold fish but I didn't know so I told her I'd ask the girl that helps with my fish. <These two fish are not compatible - goldfish are cold water fish, whereas swordtails are tropical species. I would strongly suggest that you do some more reading at this point, as many of your questions are very basic and fundamental.  I don't recall if I suggested it to you already, but if not, I would highly recommend you either purchase or check out from your local library David E. Boruchowitz's Simple Guide to Freshwater Aquariums (http://www.amazon.com/gp/product/0793821010/sr=8-1/qid=1150753336/ref=pd_bbs_1/002-4720261-3501636?%5Fencoding=UTF8)  This book discusses the nitrogen cycle in a very easy way to understand, as well as different species of fish and which are compatible with which others.  The only qualm I have about suggesting this book is the author tends to advocate overstocking tanks, in my opinion.  Aside from that, the book is an invaluable resource. I don't at all mind answering questions, but you must also take the initiative to research the basics on your own.  Good luck, Jorie>

Angelfish 'n Platies Crew, I read the post & Sabrina's reply to the reader with an impressive collection of FW fish in a 58G tank. <Say my name, and magically I appear!  Sabrina with you, today> Among the multitude of fish in the tank were angels and platies and swordfish. Over the years, I have never had much luck keeping angels and platies/swordtails thriving in the same tank. My daughters have taken over the FW in our house now that I have moved to SW. My 10 y/o wants an angel and a swordfish, but I have resisted so far. <One swordtail wouldn't be a very happy fish - they really like/need to school.  Two females (or more) per every one male.  At that, one angel wouldn't make for a very happy critter, either, I'm afraid - and angels will eat baby swordtails, so don't plan on raising many.  On top of that, two angels in a tank will likely try to breed, and will turn aggressive to their tankmates.  I prefer to see angels in larger tanks where they can have space needed to establish territory if they do breed (at the least, a 55 gallon tank, IMO, to try to have other fish with them).> Am I correct in my understanding that their optimal pH and hardness ranges are different enough that it is difficult to keep them together? <I wouldn't think so; platies, swords, and angels have been bred in captivity long enough that they can tolerate a very wide range of pH and hardness.  Angels will tolerate pH much lower than the platies and swords, and the platies and swords can go with a much harder, alkaline water than the angels.  Platies and swords can even go brackish.  But I definitely think there's enough neutral ground to keep them together (as long as you're not dealing with wild stock).> Also, the fish guy at the local Petco tells me that the hardiness and general health of the swords and platies available at retail had been going down in the past few years, probably from genetic problems. <Likely true.  The same can be said for guppies and mollies, as well, I would think.  Too much selective inbreeding without taking care to add in fresh genes.> I've been hearing similar concerns about angels recently - too much inbreeding for certain desirable traits leading to problems with other genes. <Exactly.  I've even seen in stores in the last couple of years angels with very significant deformities - missing or malformed fins, malformed heads, etc.  If possible, try to get angels from good, reputable breeders instead of from stores where some of the angels exhibit deformities.> Thanks, Steve

Swordtails Thanks for the advice. I will continue to keep an eye it and I will begin to feed all my fish some thawed frozen peas. On another note, I have a male and a female red wag swordtail. The male, when I first bought him, was so timid that he rarely left my Anubias plant. He slowly got more energetic and lately I have seen him doing his mating ritual of swimming backwards incredible fast quite a bit. His partner is obviously gravid and he rarely leaves her side. I just added two beautiful sunset platies (male and female) and he does not seem to like them very much. He is not terribly aggressive, as he does not constantly chase them, but when he does, it is usually quite violent. I noticed a nipped tail fin on the female and I cannot quite figure out what is bothering him so much given his previous timidity. After I saw the nipped fin, I isolated him in a breeding net and I plan to keep him there for a few days. I have not had much luck with this method of calming the fish down, however. Would adding a few more female swordtails help the situation? <A good idea... one or two more females> If so, should I add them while he is in the net? Or, should I wait and see if he calms down first? Thanks again for all the useful advice! -Brody <Mmm, either way... but likely better while the male is isolated. Bob Fenner> 

Aggressive swordtails 8/9/05 Hey I have a 15 gallon with 3 "teenager" marble Sailfin mollies, and 6 swordtails (2 red-white, 2 green, 1 black, 1 pineapple). I have 3 males and 3 females, and I know that the female ratio needs to be higher, so I put 1 male in my 10 gallon, but my males continued to be very aggressive. <Happens... ratios are better at three or more females per male> The mollies seem to have nothing to do with the swords, and the swords are not aggressive toward the mollies. <About right> So I continued to watch them and the "bully" male is quite larger than the other 2 males, and 2 females. He chases around the two males and the two smaller females. However, the large female chases him around!! So is there anything you suggest before I can find some time to find some new healthy females to add?? Thanks. BMERANG <Separate the bully... in a hanging net, breeding trap, floating colander in the tank. Bob Fenner>  

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