Pregnancy In Female Livebearing Fish

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Pregnant guppy

Pregnant platy

Pregnant molly

Pregnancy in live bearing fish is much different and less traumatic than the same process in mammals. Fertilized eggs develop inside the female fish without a placental connection, and they have no parenting instinct. In fact, live bearing parents will eat their unprotected fry.

Most livebearing female fish drop fry about once in every 28 days, and they can deliver up to three batches after only one contact with a male. As a result, mature females remain pregnant so long as they are healthy. Right before dropping fry, the gravid area near her vent becomes flattened.

In normal circumstances, live bearing fry enter the world, often at night, as fully formed individuals capable of living on their own. Their first instinct is to swim to the water surface. A large raft of fast growing plants at the water surface will provide the fry a refuge as well as some microorganisms to eat. Plants like hornwort, water sprite and anacharis also improve water quality by ingesting toxic nitrogen compounds.

A female live bearing fish placed in a breeding trap or moved to another aquarium is likely to suffer stress. This in turn can lead to premature delivery, and fry are born with yolk sacs not yet fully consumed. Often they fall to the bottom and drown. Dense floating plants eliminate the need to inflict stress on the female.

Image credits

guppy - Stephanie

platy - cookk

So... what do you think? Please leave me a comment or give me a


  • ZachAttack: Very informative, my one female has been delivering fry ever since october without any contact with the male.
  • ziggy_h: another grate blog on M.A.C i know everything know because of blogs like this on this site
  • arnabbar: wow great information.i really looking for like this block for a long time....really helpful.
  • ScottG: Great blog there seem to be alot of people asking about mollies reacently!
    i myself have become a molly dad for the second time in 3 weeks and i have left my females in the comunity tank all through her pregnancy i then catch the fry and place them in a breeding net for about two weeks before moving them to my nurseary tank untill they are big enough not to be eaten by the other fish or move on to other people i currently have 34 fry 25 born 2 days and 9 from a previous batch a few weeks ago that i didnt see until most were already eaten.
    i noow have 25 black mollies and 9 white mollies. All born in the comunity tank in long bushy pants that go all the way to the surface of the water.
  • meetamol: Very useful John....
  • Diane: I have a black molly who is currently trying to give birth. She is still in the pond outside with the other fish - has lots of plants - she has been swimming around all day with what looks like half a fry nearly out but not quite. Mum Molly is huge and is having trouble swimming. Is it normal to be in labor for so long...? If I put her in a tank she will stress but I don’t know if I should take her out and try and pull the fry out, hoping that this may help the others come out? Just seems to be an awfully long time to be swimming around with half the fry half in and half out... I’m new at this so was hoping someone could advise me :)
  • thea: Diane
    I will not comment on the stuck fry as I do not keep mollies but if you post this question on the forums I am sure someone will be able to help you and you will get an answer quicker. My gut says leave the mom to do her thing...trying to extract the fry may hurt her but I may be wrong as I have no experience in these things.
  • Diane: Thanks Thea, appreciate you quick response. I will wait and see how she is in the morning.
  • fish keeper101: that is great information!
  • Snarggle: How soon after giving birth can a female guppie become pregnant again? Also, can guppies suffer from inbreeding problems?
  • johnarthur: They usually stay pregnant, because live bearing female fish can deliver up to three batches of fry after only one contact with a male.
  • Snarggle: We are going to need a bigger tank....this batch yielded 8 fry...and the male is going after the female allready....doing his little tail dance and bumping the female.....
  • LEIGHZ77: Great advice thanks,needed this too as I’ve got female endlers due to drop anytime soon!
  • niks007s: Great info. Now ready to start a breeding tank.
  • Snarggle: I need some validation of the info I got at the LFS...they said if you put a group of guppies in a tank the dominate female will turn into a male...and that the guppy fry can be born pregnant...I know this is true for some insects and jelly fish....but those are much simpler creatures...the lady at the store did have a really long pinky nail, so I take the info with a grain of sand......thanks
  • johnarthur: If it’s true it’s a surprise to me. Live bearing fish do, in rare cases, appear to change gender. Female guppy fry become impregnated early in their lives and usually stay that way.
  • Snarggle: So I’m doomed...I gave my 2 males away(to my sister) after the second batch of fry poped now my 5 are 18 in a month or so
  • johnarthur: Female live bearing fish can deliver up to three batches of fry after only one contact with a male. Fry will survive if you float lots of hornwort.
  • Snarggle: this morning i woke up to 5 more fry bringing my total to a month and a half....Think i need a turtle
  • Natasha: Fantastic blog, i had no idea that putting them in a breeding box before she is ready will make her prematurely give birth. Thank you for this :)
  • Bonnietaylor: great info
  • myhorsebelle: I love your blogs, they are so informative. I only hope that someday I can be as knowledgeable as you are about all phases of aquarium keeping. My guppies have had fry 3 times now. The first time they dispeared the first day, the second time I have 3 fry that have survived and gotten some size to them, and then this last time I have managed to keep 6 of the fry. I had them in my 10 gallon, which is my quartine/hospital tank and I had put an Angel in there before I saw that we had new babies. Before I could get them out, he managed to have a good meal! I have been dealing with baby Kribs the past few weeks. Of course they are not livebearers, Mom and Dad are excellent parents and even though they are in a community tank with Angels, Gourmais etc, I still have about 40/50 babies getting some size. They are starting to swim out of their swarm and the parents protection so I guess we will see how many survive. Baby fish are allot of fun. Keep up the good work.
  • Miriam: Thank you that helped so I will not put my fish in a net let her go naturally, so she won’t get stressed.
  • Miriam: Question I set the tank up I added this liquid the pet store told me to API Quick Start , what else should I purchase sorry to bother I just don’t know this was a gift for my sons graduation he wanted fishes.
  • Miriam: Helpful thanks again
  • Sova: "live bearing fry enter the world, often at night" _ I think this is not correct_ last week i.e. 17.6.13_ My black molly give fry at day, i watch it,.. she ate 2, but i save more than 30 little fry.
  • briantheref7: As the blog says "most often at night". We have had 3 batches of fry, 2 batches born during the night. the 3rd batch, we are still catching the fry 2 days later.
  • Miriam: Great bog, my Mickie platypus had 15 frays during the day not sure if there were more but that’s what I got how will I know she’s done

    Thank you for the information, very helpful

  • Help me please: Hello johnArthur!
    one of my guppies dropped 3 fry’s last night if more they were eaten however,their tummies are still fat and their entire gavid spot is black my question is will it be dropping more today or tonight since this is the 30th day,when I saw the fry’s they all were on the bottom.
    johnArthur one thing concerns me the fry stay on the side where all the fish spend a lot of time and most of them sleep on that side at night.Should I have the pet shop to put some hornworth together to float and what can I do for the bottom of the tank as to hiding spots for them.
    I’m happy knowing the green peas helps constipation in fish,my experience was my female platy&female dalmation poop would be thick round and long it’s been a while I let one meal be green peas last wk.the platy had the longest poop I’ve ever seen it was nearly four inches long now the platy and all the fish poop isn’t long and looks thin as a peace of thread.
    one more question I put a peace of lettuces in the aquariam hoping to have many snails to do away with there was only seven,I don’t mine having some just don’t want the tank over crowded what should I do.
    Enjoy your week.
  • johnarthur: Livebearing females uaually but not always drop all of their fry at the same time. Since fry instinctively swim to the water surface, a large float of hornwort or other bushy plant will protect them. Here are a couple links that should help answer your questions:
    If you post questions in one of the topic catagories, you will probably get more answers than you will posting them as part of a blog. The linked materials should at least get you started.
  • jess: This was a really easy to read and informative post, I have a balloon molly due any day now I moved her into her own maternity tank half way through the pregnancy and scooped her it with a cup instead of a net as not to stress her, it seemed to have worked as she stayed really relaxed and continued with the pregnancy :D
  • Agnoble: Please how will I know my guppy has finished having her fries. I came from work and noticed 8 fries and one 1 dead fry. I have taking the mama out of the trap thank to put others that look likely to give birth. I am not sure if the first mama has finished delivering. I have waited 6 hours though nothing more
  • KMAC5: Great info for the beginning breeder.
  • skyprincess: How long does it take for a guppy to drop? She looks like shes going to pop and has had "pink plug" coming out for three days now.
  • Abhishake: Thank you so much sir,for your help.
  • vanessavelez6: really helpful and informative.
  • Abhinab: IT HELPED ME A LOT....THNK U....
  • babymollys: she dosent have a gravld spot but the lady at the petstore sald she was and she very fat and she has all the syptoms of a pregnet flsh thats ready to drop fry anythlng l can do or feed her to lnduce the labor
  • debcc: babymollys: not all fish will have an obvious gravid spot — a lot depends on their color. There is nothing you can, or should, do to try to hurry her along. Let nature take its course. If you stress her out by trying to hurry her along, the results could be very bad.
  • Jacquie: Hi,I have three guppies two yellow cobra females and a blue tuxedo male I have been wondering this forever I hope someone can help my two females have looked pregnant forever they have been in tanks with other males and they both have gravid spots so I am wondering if they are pregnant please respond to me as soon as possible
  • johnarthur: If they are healthy, the female guppies are pregnant. They often drop their fry at night then join tankmates in eating them. Thus you may never know the fry were born. A large, dense raft of floating plants will provide a refuge for the fry.
  • SumthingsFishie: Good read. I breed live bearers and have tried breeding nets and traps vs none. I always have way better luck with them when they are not confined which stresses them and I’ve seen them EAT babies before they had a chance to reach safety in the traps. I no longer use traps or nets.
    Instead, I use heavily planted tanks where the fry can hide. When I know mom’s getting ready to give birth, I shut off the lights to reduce her stress and so she won’t chase fry and eat them.
    I feed mom heavily with high protein foods like frozen/freeze dried black worms, blood worms and Repashy foods.
    It works!
  • MyFish: How do I tell if Tetras, or Dalmatian Mollys are pregnant?
  • johnarthur: Tetras don’t get pregnant, because their eggs must be externally fertilized. Pregnant Dalmatian mollies will have the same indicators as other livebearing female fish. However, the balloon molly does not occur naturally and is the result of selective breeding, inbreeding and culling programs. Their unusual shape makes pregnancy difficult or impossible to detect.
  • Ilovemyfish13: Ok thank you so much.
  • Jacquie: So yesterday evening i was feeding my fish and noticed a baby fish so i began looking for fry I found a few and i had to go to bed,the next morning i looked and saw allot i caught what babies i could but i had to go to school. When I came home I removed the adult fish and placed them in containers and continued looking for baby fish I caught 23 fry not counting one that had gotten squished I cannot figure out who is the mother as I have alot of females one of my cobra guppys is allot smaller though.How can I take care of the fry and what should I do? I have hikari first bites for them is that enough? Do I have a good number of fry? please answer my questions as they are needed for the life and well being of my fish
  • guppy man: love it.
  • Tamar: when I put my pregnant placy in a trap she got really stressed and all the fry drowned or were yolks. I find it easier to put more plants in when females are due and let them birth on their own accord
  • johnarthur: Unless it’s done very carefully, moving a pregnant livebearing fish into a trap or different aquarium can be very stressful for her. Stress, in turn, often causes the premature delivery of fry that can’t fend for themselves. Such fry usually have yolk sac remaining and are thus unable to swim.
  • SeaTea161: Nice Blog
  • Vicky Sauer: Okay, this is the only way I can get it out for this by making a topic
  • johnarthur: Hi Vicky: It’s OK if you write another blog on a similar topic, or you can just add your comments here.
  • MJTom: Thanks for a good info.
    My platy dropped her fry 2 wks ago. Her tummy is still big.
    Like she’s still very pregnant.
    It looks like there’s still orangey round thing inside still.
    Could she still be pregnant?
    You said they carry for 28 days,
    I don’t think she dropped any since then.
    My other platy who dropped her fry 5 wks ago had a small tummy after giving birth. Like it’s been emptied.
  • johnarthur: Livebearing female fish do not always drop all their fry in a short period. Some can spread it out for several days.
  • Amanda: Thank you! This was incredibly helpful!
  • paige.waddell: good job
  • Kathy Lawyer: I have a platy that seems to be pregnant but I’m not sure. Just in the last couple of days she stays on the bottom of the tank (and actually looks like she’s dead) or stays in the house, buts comes up at feeding time. I really don’t know if she’s pregnant or not, what should I do and how can I tell if she’s pregnant or not? Thanks, Kathy
  • Fishobsessed.: Hi Kathy Lawyer,
    I would advise you to use the "Ask A New Question" box at the top of the page, it will be seen by more people. If you could add a photo to the question as well that would help :-)
  • Anita G.: I have been keeping live bearers since I was in the 6th grade! Started out with guppies and now I have a 25 gallon fish tank full of young platys. They do not eat their fry. As a matter of fact, I have too many! I have around 5 floating artificial plants floating on top which helps the adult fish not eat as many fry. I enjoy watching the fry grow into different colors. I have a mix of red with gray and silver!
  • johnarthur: Preying on fry seems to be affected by the aquarium environment, species and individual personalities, but plants tilt the odds in favor of the fry. Recently I read about one species of livebearing fish where some fry prey on others while still inside mom. Natural survival techniques may seem bizarre, but they still work.
  • MJTom: I have 2 female platies that drop fry every month without fail. One drops every 25 days and the other every 30 days. We try to save what we see and transfer it to the nursery tank. My husband saw a fry swim out at feeding time (adult tank) what looks like a month old fry. Amazing!
    John how come my fry turns all into males?
  • johnarthur: In some species, gender is determined primarily by water temperature. This is not true of all fish and mammals but would make an interesting topic for a research paper. The latest edition of Tropical Fish Hobbyist magazine has a small blurb about the temperature/gender relationship.
  • DeeAnn (DeDe): Hi, I got some mollies from petsmart going on 4 months now. I got 3 males and 2 females. The females seemed to preg. when I got them. That was middle March/ April.... There bellies are big! Why!! haven’t they give birth yet. I take care of the water as I should. They have been hanging around the heater for 2 or so weeks! HELP!!
  • paige: they will give birth when ready
    i recommend getting a divider for the tank.
  • johnarthur: Often, female livebearing fish drop their fry at night, then ma and her tankmates eat them before sunup. That’s why I suggested adding lots of bushy, floating plants like hornwort. Little fish can swim through or around those dividers, and larger fish jump over them.
  • MJTom: Thanks for your answer John. I’ll check if there’s literature out there regarding gender etc.
    remember I said I have 2 prolific female platy. One drops her fry at night lucky her fries seems to be stronger so I see a lot of them survive. But one drops during the day and seems to wait until I get home - funny.
    I don’t know how it happen but her last drop it was 120+ I didn’t think it could be that many. But she drops 2 at a time one gets eaten then I managed to save the other. But after they’ve eaten about 25 they left the fries alone.
    So I manage to save most of them.
    Now I jut leave it in my mother tank coz I have population explotion now. the fries swims with the adults and they don’t seem to chase the little ones anymore.
  • Lisa5: I have 5 dalmation mollies in a 29 gallon tank. Ive had them for a month. 2 are pregnant im pretty sure but not possitive. 1 of my pregnant mollies will swim and then rest on the rocks. She will get up and it looks like she is swimming against a currant but not going anywhere then will lay on the bottom for a while. Could she be in labor? Or sick? My other fish are fine.
  • MJTom:

    Hi Lisa, It would be a good idea to start different thread; At the top of the page look for, “Ask A New Question”, it will be seen by more people. If you could add a photo to the question as well that would help and water quality etc... Fish will drop their fry when ready. If they’re happy pretty much every month. Goodluck!

  • torilee: I’m new to live bearing fish and what I have just read has awnsered every question I wanted to ask . thank you.
  • Aayush Sundas: hi johnarthur: i really apprecite your work. You really help people by solving there problem with fish. love you company. it mean alot to me. you are a nice guy...
  • johnarthur: Thank you. That’s very flattering.
  • C11611: I am very new to aquariums and pregnant mollies. This was the best information I have ever read. I was about to put my pregnant Molly’s into a birthing tank. Wrong thing to do. Thank you so much for this information
  • Mr Mike: I’m also very new to this, got the tank and fish for my daughter only to fall in love with the whole fish experience personally... Thanks for the photos and the thread... 👍 I have a platy that I believe is pregnant and I’m on my way to get the hornwort...
  • Toni Beales: Very interesting. Thax, helps me wiv my pregnant fish : )
  • johnarthur: Thank you for looking at the blog. For some reason, most people just ignore them.
  • MJTom: John you did a great job. Me and my hubby are totally hooked now after 2 years. you’re one of the most helpful people here. so far I’m successful with breeding platies and free adoptions are well under way 😊😊😊
  • Cwoo897: what kind of guppy is the first one? I have one exactly the same
  • Nana Christine: What does horn wart look like? Doe you use frozen peas thawed and cut in half? 12 fish in a 10 gallon. My 2.5 gallon tank had two guppies and when I was out of town for three weeks 10 fry found when I got home. They had floating plants and fed twice daily. Flake food.
  • Nana Christine: What does horn wart look like? Do you use frozen peas thawed and cut in half? 12 fish in a 10 gallon. My 2.5 gallon tank had two guppies and when I was out of town for three weeks 10 fry found when I got home. They had floating plants and fed twice daily. Flake food.
  • DeeAnn Whitley: Thanks for getting back to me. I no longer have them. I took most back to Pet store.
  • C11611: I have 2 female black mollies that are pregnant. The last time I had a black female pregnant the males just pestered her so bad when I came in the next morning she was upside down in the tank period without delivering her fry. This time when they started pestering the females I did move the females to another tank. They are doing fine. It has been 3 days. They are eating well. But they have not dropped their fry. I just was afraid I was going to lose them again. I will let you know how it all works out.
  • Jahoe04: Well, being that its been years since i had guppies, in bred in raised them. Im over 50 now in im looking for a hobby. (I GUESS) I have 3 tanks and one i have baby turtles. the other one i very large, with a double filters. Dont kn ow the size actually. In thats why i have many questions.

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