Breeding Mollies: How to breed Molly Fish successfully in home aquarium


Mollies (Poecilia sphenops) are one of the most common aquarium fishes. Because of their growth and prolific breeding nature, they are also considered one of the most sought after feeder fish (used as live feed for carnivores). They like to live in groups, often happy with more than 4 pairs. Like any tropical fish they like temperatures around 80 degree F (27 degree C). Neutral to slightly alkaline pH (up to 8) are ideal. Some aquarists will recommend you to add a teaspoon of salt per gallon of water, but if you have a water that has hardness of potable quality, that should work well for mollies. Like other live bearers, mollies breed readily in home aquaria without much difficulty. In fact most female mollies are pregnant most of the time! Here is a quick guide if you are wondering about basics of molly breeding.

Procuring breeding pairs:

Since mollies are live bearers (directly give birth to young ones), it is easy to select your breeding pair. If you go an aquarium store, you most likely will find pregnant mollies swimming around. Rounded abdomen is the most evident sign of a bearing molly.

How to tell if the molly is male or a female:

With babies in the belly, females look bulkier in the abdomen than males. Females are generally larger than males. Males have something called gonopodium in the anal fin. Gonopodium is a tube-like copulatory organ that inserts sperms into the female’s body to fertilize eggs. So when you see males chasing females with anal fin bent in the opposite direction, you know they are bound by nature’s course :)

Water conditions:

Water pH of 7.0 – 8.5 are considered good for mollies but we recommend pH up to 8.0 for breeding. Once you procure your breeding pair, let them stay together for a couple of weeks. If you are procuring pregnant females, you can isolate her in a 10-15 gallon tank.

Preparing tank:

Provide lots of hiding for the babies. Live plants are the best bet. Lots of plants planted close to each other make good hide for babies. Live plants also give mother and babies enough algae in an aged tank. This serves as natural food for them. So aging tank for few weeks to months is also beneficial in more than one ways. You can also use commercial fry-traps for this purpose. Special plants called baby-hide are also available at your pet-store. Mother might eat the babies right after the breeding, so if the babies do not have enough cover, they might lose life to the mother who gave them one!


Female will give birth to young ones by twitching her body. Young ones start swimming right away. They start to feed upon algae right away. You should remove the mother from the tank because she might try to eat babies if not enough hiding is available for babies.

Caring for the babies:

Since babies start feeding right away (they do not have  yolk sac as in egg-laying fishes), it is important to provide them sufficient food. Live feed like newly hatched brine-shrimp, or daphnia etc make good feed. But well grown algae on the plants and aquarium surfaces is enough for the babies. They also can eat any pelleted feed provided the pieces can fit into their mouth.

Hope you start seeing baby mollies soon!


How2BreedFish Team

More reading:

115 thoughts on “Breeding Mollies: How to breed Molly Fish successfully in home aquarium

      • Hindi nangingitlog ang molly or guppies. direct silang naglalabas ng fry.

        mollies and guppies are not giving birth by eggs. they give directly a fry.

        • no i was had 2 sword tails and i have put them in the mollies tank but the mollies was chasing them and the have jumped out the mollies tank then i put them in another small tank…-_-

      • I have brought mauli it gave birth to 30 mauli in a small pot after some time they all die few of them very dead only when they came out after 5 hour it gave birth to 1 fries which was also dead when he came out some please give reason what should i do should i bring big tank for breeding.

    • All u need is a good tank and fresh water.. Proper oxygen.. And feed them time to time.. Rest of things leave on them..

  1. is oxygen necessary to breed mollie fish. & can diff types of molies be kept in th same tank for breeding.
    pls answer

    • Oxygen is not necessary, different types of mollies can be bread together (you see the mix and match mollies around right?)

  2. My molly has given birth to 20 fries yesterday.I have isolated them in a separate bowl and the are moving randomly.Now how will I feed them or should I keep them in fasting for a week or two?

  3. you know, i had about 8 mollies (3 males, and 5 females) in my 10 gal tank and without even trying my mollies had babies! they have been in the tank since i bought them, for about 3-4 months, but sadly, i had plenty of places for the fry to hide, but they still got eaten, now i havd 1 fry on a one gal tank, and all of the females in their own 10 gal tank. so maybe i can isolate the fry so they can actually grow!

  4. my mollies gave birth to 20 babies
    i put like one tea spoon of fish food its very thin sheets
    is that is good?”day by day”

    • You might want to crush these thin flakes. They are not the best for the babies, because size of the food particle and babies’ mouth size do not match. But your tank may have some zooplankton that babies may feed on.
      Live food is ideal for babies.

    • Quick answer for that would be this: All the food should be consumed within first 15 minutes. Use trial and error starting from small amounts. You may be surprised to know that most of the toxicities/mortality in fish tanks result from excess food rather than scarcity of food… Good luck!!

    • Daily is okay, but if you were to go away for a day, should not be a problem at all. More than anything it depends on how you develop their habit, they will get used to a routine and expect you to feed them as usual…

  5. Hi my mollie is very pregnant i have her in a breeding net so the babbies dont get eatin! i want to know how long b4 she gives birth? her belly is HUGE! very big bubble,will she be ok? is the something i can do to help her give birth? pls help, thank u :)

    • Depends on how long your molly has been pregnant. Nature will not hurt your molly while it is pregnant or while it gives birth. Just feed her well and keep water quality optimal

  6. I had 4 mollies 2 white and 2 orange they live with shark fishark fish
    the fishes were dying one by one dont know why what should i do i had left only three molies and one shark

      • A male guppy will try to mate with your female molly and he will succeed, I have not yet seen a male molly try to mate with a female guppy. The offspring are called Muppies, I believe they are less fertile to completely sterile like most other hybrids in the world. I have gotten many fertile ones and continued the strain with those individuals, they tend to look like a molly sized guppy with less color. I really hope that one day I will get some guppy sized mollies! I hope this helps.
        ~ Betta

  7. I have two dwarf mollies. The female gave birth to a fry four days ago. I isolated the fry in breeder tank. How many babies to they usually have? Should I put her back into the breeder she looks pregnant still? Also could you recommend some other sites or books, yours has been very helpful. Thank you so much!


    • she may still have zero to half a dozen babies depending on how long it has been since the first baby in this batch. baby is safer outside of her mom, but the baby needs something to eat too. fish food organism (tiny plants and animals in the water) will be its food… she will look pregnant may be from this batch that is yet to be delivered or from a next batch that will be delivered in a month or so…

  8. hello dear,
    i hav read ur information that been given. and found it very helpfull. thank u very much. but, one thing pls inform me. one of my female is not giving birth. she is carryng a huge pregnancy. but not giving birth. she is pregnent more then 4 months. but not giving birth..
    pls, tell me. now, what i should do?
    thnx again.

    • Hi,
      Very likely that water quality or nesting conditions are not conducive for her to give birth. Check this and other posts on this site and other sites and make sure you have the right conditions. It is more demanding for a fish to hold a pregnancy (and re-absorb it) than giving birth, so it better deliver…

  9. I’ve had mollies and guppies since last year when my old teacher gave them to me. He said that they had babies a lot and his tank was constanly full. I clean my tank every 2 days because the water turns a dark green and the fish are slowly disappearing and not coming back… I also have 2 catfish, 2 black moors and 2 calico fantails and a dragon fish in the same tank. Help!

    • Hi,
      Sounds more like one of your other members is eating guppies/mollies. You have one of your water quality parameters not set up right which is causing your tank to green-up. Too much of nutrients, too much direct sunlight, too much of feed all can cause this

  10. Hello there,

    this website has been very helpful. One of my molly gave birth to 17 which i have kept on an isolated container. Can you tell me if a heater is a must for the babies in the separate tank, as i just have one heater which is in my main tank that includes a sea angel, couple of tetras and 5 mollies.

    • Hi, you need a heater (if you live in a place where temp goes below 15degreeC or so outside, you need heater more in baby tank than in the other one. goodluck, raghuveer

    • Most likely you will notice them, I like to move any of my heavily pregnant live bearers to a birthing tank about one week before they are due, try to provide some cover for the fry. If a female that was pregnant suddenly turns up skinny like she had her babies she either had them or aborted her pregnancy, if you do see this then try looking around the gravel, mine also seem to enjoy it next to the heater and I have found many hiding behind it too. They do eat the algae off of tank walls and ornaments, so if you have any spots with algae try looking there too. Hope this helps!

  11. Hi,
    im from kerala while seaching the internet i saw ur site
    im having 6 mollies,3 of them are black mollies(1 male and 2 females),1 dalmation mollie which is a male ,2 silver mollies(1 male and 1 female)!!!
    how much females do you suggest for a male mollie
    can the mollies cross breed other mollies example=can Male black mollie breed with silver female mollies and other livebearers like platy,swordtail,guppy etc….
    plz reply eager to breed them and make hybrids

  12. I find java moss a must for any fry. I do not seperate all babies and have great results. I have bread my 4 mollies very well

  13. Hi Raghuveer,

    I have 2 black molly,2 orange molly,4 white molly and 2 Gowra in my fish tank. Totally there are 4 males and 4 females. I have spreaded with mud in the surface and planted with a Hydrilla. It has grown a lot so that it will be able to provide hiding spots for fry. Two females white and black got pregnant for more than 3 weeks and sterday i found the white belly came to normal but i couldnt find any fry in the tank. Black is still moving around with its swollen belly. What happened to the white molly fries? How should i protect this Black atleast before she gives birth? Please suggest…


  15. i have a female white molly and its stomach is bulged like a bubble………..i dont no that its pregnant or wat…………..can anyone just help me to find out………………:-(

  16. Hie i just bought 2 mollies a day back and one of dem were pregnent nd she died in just one day, will d other one stay without a pair or no ..???

  17. Hi. First of all it’s a very good post. I have four tanks outside my house and I put different mollies ang gappys in it. Some gave birth. But sadly most of my elder mollies with big sized bellies are got died when its about breed :(
    I don’t why it’s happening!!
    I lost my lovely mollies

    Is it any problem it’s staying together with all others or problems in water? The temprature is below 28•c I don’t know how to check the PH level!

    Please advice me so I can save others


  18. I have succesfully acclimated a FW mollies for my Salwater tank, YES they will do in saltwater, you just need to do a good and slow acclimation, i was happy to have 4 of them in my FOWLR so the next day i went to my LFS and grab another 6 after 2 days i notice one of my dalmatian molly is pregnant “i think so” and i hope so… i now have her in the breeding box… i will let you guys know what happen….

  19. hey gays please any one answer. today my mollie has died and i have buy tow fishes i donot know what is the fish name but she had give birth and i donot know what do i must eat the little fryes or any thing about them please help

    • I’m sorry but if you’re not going to post about fish or any issue you need help with concerning fish, please don’t post anything. Thanks.

  20. Hi, all the information here is very useful thanks. I have 23 Orange Molly babies and they have just turned 3 months … Can anyone tell me how old do they have to be for them to have babies themselves? Thanks

  21. So I have two mollies (male and female) and she’s already given birth to 16 babies. I just wonder, how long does it take for them to develop?

  22. Hello, I don`t know what`s wrong with my fish! So I have been successfully breeding mollies for about a year now, but a few months ago a few started dying. :’( and than all the sudden they were all dead! All died of the same symptoms which were: twitching violently, running into the side of the tank, and not being able to hold themselves up the right way. So I started over with new fish and all, and 2 months later ta-da! Fry! But then my male died of those symptoms, so I had to get a new one, and all`s good so far. What was wrong with the ones that died?! I do 35% water changes every few weeks and everything….

  23. I have noticed my mollie is chunky…i cant tell if it is a female but it has been agressive toward the other fish in the tank including my dwarf frog & even more agressive during feeding times. Is my fish just a fatty or is that a sign its pregnant??

    • If your fish’s anal fin is a sort of fan shape, then it’s a she. If its anal fin is a modified fin (a sort of narrow and straight looking fin), its a guy.

  24. I’ve got 1 black mollie (only the 1) with other 5 small fish a month a go she gave birth to only 1 baby, but after a month and 2/3 day she give birth to more than 10+ babays. Like I say she is the only mollie in the tank. (We think she was pregnant when we bought her), but what I can’t understand is 1 baby and after more than n month a lot of babys, what is the reason for that??

    • Sometimes, an already pregnant female molly would be sought after once more by another fish. This won’t result in a mixed batch; sometimes she simply stores the sperms and then gets pregnant again. :)

  25. I like how most of these questions are answered in the article at the top. Can you guys not see it? Mollies are like Guppies. Put several of them in the same environment, feed them and wait. That’s about all you need to do.

  26. my cousin gave me a pair of palattinum mollies, right after u put them in my tank they start mating, the male casing the female, how long it will take for the female to be pregnant? and does it need a oxygen supply all the time/. the tank has a direct contact to sun light and open aired, my cousin told me that it doesnt need oxygen supply everyday, is that true? tnx

  27. I have a single golden looking fish, I’m not sure if its a Molly. Got it sometime in early October and it has reproduce every month since which scares me

  28. Hello, I had a question about how some of my mollies offspring will turn out I have 5 marbled mollies (3 large females, one small mostly black male with white on the head, and one marbled male that has long fins and laced tail) one male gold dust Mollie, and 3 female Dalmatians who arnt quite ready to breed. Just wondering what I might get by crossing them. Also I read somewhere that long finned males can’t breed. Is that true?

  29. Molly fish is awesome fish. if u r beginner try black or white molly coz they r easy to breed. they live without aeration pump if water is crystal clean but i suggest give them aeration, filtration, heater to make this guys healthy. 1 spoon per gallon should be added. molly fry should fed boiled egg yolk crushed they love it.

  30. hi., i had 26 mollies in total 4 guppies 30 in all in one refrigerator size aquarium., i separate the fry 20 and unfortunately they all died., why? i put aqua plants to cover the whole area., put under the sun for the reason to produce algae., and i feed oftenly. and i wonder why my fry all die., and also iv seen my mollies in the floor., r they high jumper? what kind of feeds to feed them?

  31. total of 26 mollies and 4 flatties., total of 30 in 1 refrigerator size aquaruim., decorated with coral reefs and alive aquatic plants and floating aquatic plants., i separete the fry to other container coverd with floating aqua plants., i put it under the sun for the reason to produce green algae., i feed oftenly floating feeds( crushed) and i wonder why they slowly dies., from 20 fry no 8 left., and is it mollies a high jumper? coz iv seen them dead in ma floor., help me how to take good care this wriglers like baby mollies ( fry) :D

  32. Ive had my black n white mollies fir about 2 weeks now. Male and female. And yesterday i just noticed i had 3 new babies in my 55 gallon tank. Thinking bout giving the babies to the pet store

  33. will other fishes, will eat molly fish babies————–
    The reason i am asking is , because my molly fish was extra fat from 7th April to 24th April 2014, and on 25th April 2014 .She is very thin,and babies were not there.

  34. I have two young mollies in my tank. Im watching them and for lack of a better explanation it looks like one sniffing the others butt. Lol dont know how else to describe it. What are they doing?!

  35. Which fish is the best to keep in aquarium, because my 46 fishes have died in my aquarium of 20 gallons.
    Now I want some cute,big and friendly fishes to keep in 20 gallon aquarium.Can you give me the answer of ,How to keep fishes healthier,friendly and best staying fish to stay around 1 to 1.5 years in my aquarium and cute fishes.

  36. i have 2 female and 1 male mollies in a tank but they do not breeding
    i collect rainwater for them [i think rainwater is good for them] i wait 1 month no result

  37. I have a molly sailfin (half yellow and white) gets fat for 2 weeks than gets thin even i watched her verycarefully if she is pergnant and having birth but nothing happened. can someone help me with this?

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>