Aquarium Care FAQ: Is My Platy Male Or Female?

Telling the sex of a platy is very easy. In fact, the sex of all livebearers – tropical fish, including platys, mollies, swordtails, and guppies, that produce live young, as opposed to eggs which need time to hatch – can be determined in the following foolproof way.

The most obvious physiological trait that differentiates a male from a female platy is easy to spot …if you know where to look.

Male and Female Platy

If you examine the diagram above, you’ll notice that the anal fin of the male platy (the fin circled in red) looks different from that of the female platy (also circled in red). The anal fin of the male platy is called a gonopodium and looks more clamped, flat, and elongated. The anal fin of the female platy, on the other hand, is noticeably more fan shaped.

And that’s all there is to it! That’s how you can tell the sex of your platy.

Again, not only platys, but also mollies, swordtails, and guppies can be sexed in the way described above.

So, what can you do with this information?
How can you apply it to practice?

Well, livebearers breed prolifically in the home aquarium. If you want to avoid producing a continuous supply of baby fish, get only female platys, mollies, swordtails, and/or guppies. Male livebearers tend to be aggressive towards each other and, for this reason, I do not recommend getting only males.

However, male livebearers tend to be more colorful than their female counterparts (this is especially true of guppies), so you may want to mix some males into your female population. Needless to say, this will produce offspring.

If you choose to go this route, I strongly advise a livebearer ratio of one male for every two females. If, for example, you have two male mollies in your aquarium, you should also keep four females with them. Doing so will simultaneously curtail aggressive male competition and distribute (and, hence, attenuate) the physical stress of carrying babies among the females.

In other words, a ratio of one male to two females will lesson the stress felt by the females by distributing the “special male attention” that the females receive among more than one fish.

Here again, we see that establishing a balanced aquarium environment is key to successful tropical fish keeping. Indeed, aquarium care is simple when you understand the basic needs of your fish.


15 people commented on "Aquarium Care FAQ: Is My Platy Male Or Female?"
Feel free to join the conversation and leave a comment as well.

  • John says:

    Perfect. Exactly the info. I needed on sexing platys. We bought a pair nearly a year ago – one died – and I wanted to get a mate for him/her particularly since we’ve moved to a new 55 gallon aquarium. Thanks!

  • Antonio says:

    Thank You Very Much. I mean it because I wasted months looking for how to identify male and female and you helped a lot. Thank you again. bye

  • Mikaila says:

    thank you for the sexing info. After reading this I now know that I have 2 males & 1 female. I bought 4 & 1 died just after arriving home & wow what a bad ratio I have, according to your info., so I will get more asap hopefully the pet store staff will help me get more girls.

  • admin says:

    Hi Mikaila, Thanks for posting.

    Yes; 2 male platys (or guppies, mollies, or swordtails) to 1 female is not a good combination at all. This combination of livebearing tropical fish leaves the males more prone to fight amongst each other. Furthermore, the 2 males may even “harass” the female excessively on account of the disproportionate ratio (in favor of the males).

    I am sorry about your loss, and I hope you can find a replacement soon.

    If you decide to keep the two males, and if you have enough space in your aquarium, I recommend buying 2 to 3 more females to even out the ratio so that it more closely resembles 2 females for every 1 male.

    Also, take a look at this Aquarium Care Article that describes the best method for physically adding new new fish to your aquarium. The information in the article will no doubt prove useful when you get those new fish.

    Wishing you the best of luck,

  • Dee says:

    Thank you, I got lucky it only took me 10 minutes to get the info I need to determine what sex my platys are.

  • admin says:

    You are very welcome. I’m always glad to help.

  • Dominique says:

    I just realised that i have 1 female and 3 male, a friend told me that i had 3 females and 1 male! tomorow im going to go and buy more females! thank you for your information 🙂

  • Roni says:

    Thanks for the info. Very quick to find. I grew up with fish, but never had fry. My son was so excited one evening when he saw 2 babies and I had no idea how they even bred. Now we have 6 new ones in the tank and needed to figure out what to do. We are going all female. Thanks again.

  • Thomas says:

    hi! I am 13 and i breed guppies since 10 but as for platies ,swordtails and mollies, i just can see that the males are never interested in the females!!!I have 3 male platies and 7 female platies but none are pregnant… How do i get them to breed???Cos i bought mine at $2.50 each….

  • Eleanor says:

    Hi, I have 3 female and 1 male platy. My male has nibbled at one of the females who did seem to get quite fat, but is now slimmer, She may have had the fry and they have been eaten. She now sits between the filter and the back of the tank, only coming out occasionally. The male took to shadowing another female who is now spending a lot of time at the filter, and has moved on to the third. He will not leave her alone. Anywhere she goes, he goes. Should I remove him from the tank (I have a breeding box) for a couple of days, or is this normal behaviour. I have medicine for the platy that was nipped, that I add to the aquarium water. Your help would be appreciated.

  • hunter says:

    i bought 5 platy the other day and one of the males had a dark spot like the ones the females get when pregnant does that mean he is a she or what . also i bought 2 guppies i was told the female was pregnant but she doesnt have the dark spot so how do i know if she is pregnant please write me a reply i need your help

  • admin says:

    Hi Hunter,

    Regarding your male (or female) platy: The sure-fire way to determine the sex of your platy is to look at the anal fin (see article above). If your platy has a gonopodium, then it’s a male (100%), and the spot is perhaps just an example of coincidental coloration.

    Also, most pregnant guppies will display the dark spot (called a “gravid spot”) towards the back of the stomach, right in front of the anal fin.

    Keep in mind however, that the gravid spot will get darker over the course of pregnancy (it does not appear right at the moment of fertilization). Also, her stomach will noticeably enlarge. If her stomach is still small, chances are that the gravid spot is hardly as noticeable as it will be, say, one week from now.

    On the other hand, if the female guppy does not get bigger and doesn’t develop a clearly visible gravid spot, then she is not pregnant.

    But, if you’re looking forward to raising guppy fry, don’t worry. As long as a male is present in your aquarium, the female guppy will be pregnant in no time.

    Hope this info helps.

    Thanks for posting and take care 🙂

  • Ruth says:

    Dear Admin, I visited this post while researching a little ‘mystery’ in my tank. Read on….

    I bought 1 male and 2 female orange swordtails. The male had a sword, the females did not. After quarantine, I put them in a big 49 gallon bowfront tank and they had about 15 orange offspring, the oldest being 8 months. The mystery is all the offspring seem to be female (no swords), which doesn’t seem very likely. Any ideas what might be going on? Do the baby males remain latent as long as there is an alpha in the tank? Just curious…

    Thanks in advance, Ruth

  • admin says:

    Hi Ruth,

    It is very difficult (if not impossible) to determine the sex of baby fish, for they have not yet developed distinguishing male/female characteristics. When your fish get older, you should be able to see the difference – I’m referring to both the gonopodium and the distinctive sword tail of the males.

    In other words, all your swordtail fry (i.e. baby fish) will lack a sword and will have fan-shaped anal fins. Also, male swordtails are known to sometimes be late bloomers. In extreme cases, it may take up to a year for the distinctive male features to develop!

    Hope this info helps, Ruth. And congratulations on your new batch of swordtail fry.


  • Iris says:

    Dear admin,

    This site rocks!! I have been looking to learn something awesome about platy’s and Mollies and I stumbled upon this topic.. I never knew how to truly distinguish a male from the female up until now…..

    Could anyone of you cool dudes there give me advise?? My original plan was to buy 1 male Silver platy and 2 female red platy…

    My problem? I am having a hard time finding a male silver platy in any of the Local Fish Stores here…

    My solution? I will buy a male silver molly instead of the male platy.. Because the molly is more accessible to me….

    My question^_^ Will the male molly breed with the female platy? What will their babies be like?? Cause if something bad comes out of the female platy(sigh) I don’t want to mess with our mother nature..

    Anyways.. Thank you for your kind and generous effort in helping..

    Radical site! 5stars,

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