Breeding goldfish

Breeding goldfish

It’s not impossible to breed your goldfish, but it’s not as easy as breeding rabbits or gerbils.

The reason is that goldfish lay eggs in the water, rather than giving birth to baby goldfish. These eggs must be protected until they hatch, and the tiny baby fish (called fry) raised using special baby fish food.

The eggs are vulnerable to infection, and parents will give you no help, either. In fact, they may even eat the eggs, and so the eggs and baby fry will need their own aquarium or pond.

On the other hand, you can potentially raise dozens or even hundreds of baby goldfish from just one spawning, if you’ve got the time, resources and commitment.

You might even get the bug, and try and develop your own line of fancy goldfish. After all, no fancy goldfish occur naturally in the wild - they have all been developed by many years of selective breeding.

Key steps in breeding goldfish

Click on the links below (where available) for information on that specific breeding step.

  1. Choose the parent fish for breeding
  2. Separate the male and female goldfish
  3. Feed your brood stock to improve their condition ahead of breeding
  4. Prepare the special aquarium that you will use to raise your goldfish fry
  5. Reunite the male and female goldfish in early Spring in the breeding aquarium
  6. Watch your goldfish making love! Then remove the parents, and wait for the eggs to hatch
  7. Feed the babies baby brine shrimp, switching to other foods as they grow
  8. Maintain good water conditions in the fry aquarium
  9. Cull weak or deformed goldfish in order to preserve the genetic line
  10. As they grow, divide the goldfish out into more aquariums or ponds to avoid overcrowding.

We’ll be writing separate entries for each of the steps above in the next few weeks, so please do subscribe to the Goldfish Care Guide to stay informed.

Click here to learn more goldfish secrets!

Filed in: Breeding

74 Responses to “Breeding goldfish”

  1. Yes breeding goldfish is something all goldfish owners will want to try or see happen sooner or later. The only thing if not done correctly and perform proper measures that need to be done some people may be disappointed. Biggest thing is removing the parents as you mentioned. Goldfish will eat up all the eggs or at least try! People will be lucky if they have some left. Another thing with goldfish breeding is that people should add fungus medication into the water which is specifically meant for protecting the eggs from fungus. This will help with results on how many eggs that will hatch from your goldfish breeding. I remember when I first got into the hobby and my godfish just finished breeding. Days later all goldfish eggs were all covered in fungus and I got absolutely nothing from the batch. That should be something that people think about as well and maintain excellent water quality as mentioned.

    Owen you have a great goldfish care blog! Keep up the great work.

    Happy Holidays and Best Wishes in 2009


    Jamie Boyle
    The Goldfish Guy

  2. how do you know what sex of goldfish you have

  3. Yes, i ask the same question, how can you tell the difference between sexes?

  4. how do you tell the sex of goldfish.

  5. I am no “certified expert” on the matter but have learnt a lot through reading and experience. Hope some of this may be useful to other fellow hobbyists.

    There’s a lot of info on ways of sexing goldfish (do a small search on the net and you’ll be overwhelmed).

    1. Males have tubercles on the gills during the mating season (hard to distinguish at times and females sometime display this characteristic as well, just as women with hypertestosteronism & hirsutism)
    2. Body/belly size when egg-laden (well, you may as well have a very fat-looking male…)
    3. Shape of the anal orifice (often hard to distinguish, needs a well-trained eye, larger and elongated in females, some sources distinguish as concave/convex shapes etc).
    4. Behaviour: who chases and who is being chased? (In my opinion the most reliable)

    The key is in long hours of OBSERVATION. A combination of two or more signs makes it more likely that you are not mistaken. Of course, the best way will be when you actually see them breeding… Or put them in the company of fish with known sexes…

    For cleanliness of the water for raising the fry.

    The larger the water quantity you have in your aquarium the better (I prefer no less than 150 litres). Easier to maintain. I see no need to make frquent water changes if you have good biofiltration and large surfaces for bacteria to grow on (having some sort of trickle filter will help a lot).
    Medium to large size gravel will easily trap excess food for further decaying, an abundance of both rooted and floating plants is a must. It will increase the surface AND clean the water (do not forget about proper lighting, otherwise the plants will give off mor CO2 than O2 and will start to decay).

    Treating the water with methylene blue before and after hatching helps to reduce fungal infection. Nevertheless, you will still have some eggs (often unfertilised) and fry (visible fin rot) lost to fungus. But if you have saved the batch before being devoured by the parents, you will still have hundreds or even thousands of fry to select a few from.

    Last but not least, add some ramshorn & trumpet snails. They do a great job in cleaning the debris. Do not worry about them eating fish eggs. Have never seen them do that, may be they do, but considering the quantity of eggs this should not be a worry. If your aquariums get crowded with snails you can always collect a handful of the larger ones and feed them to your adult fish after crushing. They make good fresh live food for conditioning the females…

    To feed the fry.

    No problem if you have no brine shrimp eggs to hatch… Have never done this myself (none around where I live).

    What I do instead:

    (Of course you start feeding in 2-3 days after hatching)

    1. Put some banana peels in a bottle of aquarium water under the sun to grow infusoria (better have several bottles prepared before the eggs hatch, they need time to grow) I filter the water through several layers of gauze (after a week or when the water gets cloudy) and squeeze the gauze in the aquarium or throw it in the return outlet of my trickle filters. You can do the same with dried grass or hay. If you have a trickle filter, do not clean all sections at a time. This will greatly reduce the amount of nitrifying bacteria and your ammonia will jump to toxic levels at once. Also, lots of infusoria grow in the debris in the filter and some will end up in the aquairium for the fry lo lunch on.

    2. egg yolk as everybody do

    3. 2-3 pinches of flour in a cup of water. Add some dry yeast and put it on the lamp to keep warm. The yeast will get activated in no time. You can feed this (after mixing) with a syringe. Don’t worry about your water getting cloudy, it’ll settle down soon and the bacteria+snails will do the rest. Yeast supplies ample vitamin B to the fry and competes with harmful bacteria and increases the immunity of the fry. Prepare some new in 2-3 days as the previous one fouls.

    4. Keep a small (10L) non-filtered but aerated aquarium (or jar) in a sunny place, add some fish food (I also add a very small amount of potassium nitrate and sodium polyphosphate to speed up the process) and you will have a green algae bloom. Pour a couple of cups of this water to your fry. They love it.

    5. If you ever buy fresh fish for eating and clean it yourself keep any eggs (caviar) that come out of the belly in a flattened nylon pack in the freezer (you can easily crush it to smaller pieces when frozen). After thawing a small piece you can crush it between two glass plates into a milky mixture… Lots of proteins and fat for the fry. Feed this when the fry are some 10 days old.

    6. In 2-3 weeks you can start feeding them powdered flakes or dried daphnia or any other adult fish food for the matter.

    7. Do a weekly 20% water change. Ordinary tap water will do (no matter what everybody says). No need for special treatment if you keep the water for a week or so. I keep an 80 litre barrel for the purpose.

    As you see goldfish are not swordtails or guppies… They need a lot of volume and space. So if you are planning to breed and raise fry you have to plan ahead and have several large well-filtered aquariums. Caring for them is quite an amount of physical work. Nevertheless it is rewarding for those who really love fish. Getting a large batch of fry to be able to select from a few that are really worth IS in itself a VICTORY and SATISFACTION. Believe me, I am the grandpa of more than a thousand fry in a 200L baththub and a 150 aquarium at the time I am writing… IT FEELS SOOOO GOOD :-)

    Arshak Davidian
    Stepanakert-Mountainous Karabakh

  6. if not breeding gold fish how do you know male from female? and also i have a greenspotted puffer fish and i had it in the tank with the gold fish and of course it attacked the gold fish and tore some of there fins off but now the goldfish are seperated from the puffer and their fins are growing back . is it possabile fo their fins to grow back?

  7. Hi, i came home and one of fishes had something long at the back of it, i am no fish expert and i got worried that he may be sick. The long trail behind was like a greyish colour and now its at the bottom of the tank. Do you know what this was?? Im worried if its laid eggs and i would like it if teh fishes ate them,

  8. sorry i meant i would not like it if the fishes ate them

  9. Nazia’s question of June 17th.

    The trailing grey is its poo - faeces.



  11. Could someone please help me? I have a small pond with two goldfish in the garden, then just yesterday, I noticed a lot of
    babies (fry), do the parents eat their babies as well as the eggs? If they eat the fry, is there a special container to buy I can keep the babies in from harm, until they maybe reach a certain size, where the parents stop eating them?

    help very appreciated,
    thank you,
    Andrea Steinke

  12. If a goldfish is bellyup at the water surface for a few days…does it mean it is dying?

  13. cathrine its dead ! sorry :(

    im gonna start breding mine :):)

  14. if it is time for the goldfish to spawn, is it better to help them (hand spawning) or just let it be?

  15. We had 7 adult goldfish in our livestock 300 gallon stock tank. They have been there for about a year. One day we went out to feed and saw about 30 babies. Boy were we surprised to see babies. This has been fun for the kiddos to see 1) how the fish really do “grow” to the size of their environment (we do have an aquariaum in the house and put 4 fish in there the same time we did the 7 in the stock tank. The ones in the house are 2″ long and the ones in the livestock tank are 10″-12″ long) and 2)seeing the babies and all the colors that they are. The adults are orange/white or orange, or white, the babies are orange/white/black, orange/black, orange/white, or white/black, so it has been really fun

  16. Hi,
    I just got 3 5″ inch goldfish and 3 4″ inch Chubinke( I think that is what they are called) and 5 small feeder goldfish for my 1200 gallon pond. I see the larger ones sometimes go to the surface and open they’re mouth are they eating or getting air? I havent seen the small ones and I dont know if they are ok or not. Is it normal for them to come to the surface off and on to eat or what ? They seem healthy otherwise and its hard to see in the deeper water. and I didnt get Koi cause I have been told that they can be more messy and eat my plants up, I do see the Gold fish nibble a little off them but nothing major. How many goldfish should I be comfortable supporting in a 1200 Gallon pond?

  17. One of my fish spends a lot of time on it’s side at the bottom of our small pool - only seems to wake up at feeding time. It is also misshapen on one side. Any ideas?

  18. hello, can you please help me, we have several eggs that we have seen one of our goldfish laying the eggs and we separated her from the rest, after she was done spuring the eggs, we put her back with the other 12 goldfishes. Now my question is how long before the eggs hutch, there are a bunch of like hard shell little eggs on the bottom, how long before they hutch and do we have to keep the water moving with the filter? please let us know we are anxious to see if the baby fish will be born
    thank you,

  19. how do i know which are male or female?

  20. I have like 22 goldfish which r male or famale some r fat can u help out

  21. my daughter got some goldfish at christmas 4 her new dora of them seems 2 be laid on its side at the top of the tank.does this mean its dyin??

  22. I have a 65 gallon hexigon tank and a wet dry filter but it is sucking up the small goldfish. What type of goldfish, size and amount should I get?? I would like to breed them also……thank you

  23. i won some goldfish and i have 4 ,i want them to breed but idk how and me and my friend want to find out cuz 1 of them are rilly fat in the middle but its not that big in size and the all constantly circl around it and the all will constantly huddle in a corner and i need to know how to tell boy from girls! and da prego 1ns

  24. i have i pregnant gold fish now,her tummy is so big then i separate her in different aquarium,she alone this time,is it possible she can out the baby even she is alone??

  25. Is there anything you can make or put in the bottom of our 165 gal. pond to encourage the female to lay eggs, and safty for a while for the fry?

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  27. you’ve been extreemly helpful to me,i’ve always been told goldfish breeding in fish tanks can not be done.I have a 36 gallon tank plus a 20 gallon tank,is there a way i should set up my tank to make it more of a breeding habittat?and do goldfish choose eachother? can they come to you pregnant also?
    Sorry new to breeding goldfish but it’s an enjoyable hobby,I’ll be moving to Florida where they will have there own pond.


  28. Well, We don’t even try, it just happens. We purchase .28 cent goldfish at the local big box store so they can eat mosquito larvae in the horse trough. I also put them in our fake outdoor pond. They grow quite large. Last year there were 2 dark brown small fish that just appeared one day! They eventually turned gold! This year…same thing but there are 3! They are still dark and tricky to see. pretty cool.

  29. i would like to know how long is the incubation time from the time the eggs are laid til they hatch.

  30. If your fish is floating at the surface of the water, either on its side or belly up, it is definitely dead. fish do not have baby fish, they lay eggs then the eggs hatch into little fish, but the parents will eat the eggs unless you remove the parents from the tank.

  31. how long befor the eggs hatch

  32. i have notice the last 2 weekes of sept. my goldfish or koi wont come up to eat what does mean

  33. Message for Gentle Ben
    Gold Fish love to breed by swiming over floating water plants
    the more plants the better. After the fish are finished with the
    breeding time about one or two days, just take the plants out and
    place in a tank. In about week are so the fry will hatch. Wait
    about 7 or 8 months before returning fry to the pound. If you leave the eggs or the baby frys in the pound most will be eaten.
    This works ( floating water plants )for breeding Gold Fish in a “TANK” as well. Plants also help fry to hide if left in with
    much bigger fish note: Gold Fish eggs will stick to most plant surfaces.

  34. I have 3 goldfish in a bowl.Do I need to put them in a tank with a filter?

  35. Can you mix small, medium,and large goldfish?

  36. Austin, you can not have 1 goldfish in a bowl :)
    so yes you do need to get a filter ;)

  37. liz you are so smart! ;)

  38. i have a fish that we think is pregnant, but the fish has been pregnant for so long when will the fish lay her eggs?

  39. Are you insterested in link exchange with my blog? Thank you.

  40. We have a large stock tank, and bought a few feeded goldfish, when we moved a year later I broke the ice on the tank and moved the two goldfish to a 50 gal tank inside filters and everything. It was a lot warmer of course, and I put a bunch of fake flowers in the tank also. This was about three weeks ago, last night I thought I saw babies in there about four I counted. I took the adults out and put them in another tank and this morning I have about 100 babies in there. sure was a suprise. I am not doing anything special. we did’nt even know we had a pair. I would be happy to let you know how it turns out for us, if anyone is interested.

  41. Does anyone know how long they spawn. They were acting goofey again last night, so this morning when they were calm, I checked the little tank, and there was all kinds of eggs again on the fake flower I put in there. I took the fake flower and put in the baby tank. Guess we’ll see what happens. There is still a hugh passel of babies in there, they cling to the sides of the tank mainly. Anyone know why. I honestly don’t know anything about fish, except its calming to me to watch them. Thank-you

  42. Well written report, and i already understood that some groups are more liable than others (since many of us are different) would share the same idea. I hope you keep this blog operating well.

  43. It took three days to hatch out the second batch of babies. So far everything is going fine. I feed the babies powered flakes in the morning about 1/3 of a teaspoon. In late afternoon I feed them a brine shrimp cube that I melt in hot water, because I keep them frozen. Thats about all for now.

  44. I brought a new female goldfish today evening at 7:30 pm. i already had a male goldfish. At 8:30 i saw that my female goldfish has given birth of 15 cute babies. not egg. how do i take care of these 15 babies? please hep me. i already lost my two favorite goldfish due to someone else. thats why i brought a new pair. i got 15 beautiful baby goldfish also..i do not want to loose them..please help me.

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  46. Pl help me. I have 4 gold colour faintail fishes and 1 white faintail,in the fish tank for many years. Sometimes it trouble me by seeing 2 or 3 fishes chasing and “sniffing” at the tail of the white fantail fish. Does it mean that the white fish is female and ready to lay eggs? I keep disturbing them as I don’t like to see them “bullying”. What does this mean and how do I solve the problem of “bullying” in the tank?.HELP!!!!

  47. Austin said:
    Can you mix small, medium,and large goldfish?
    I believe I can answer Austins guestion. Yes you can. I use my Wolfgang Puck all in one food processor/blender, it works very well for the job.
    Just thought everyone might like a little humor.

  48. hey everyone, i just got three fantailed goldfish from my friend and i believe that two are male and that the third is female (because shes real tubby around her midsection while the others are not. and from many sites that i have read it definently seems like shes carrying eggs, also the others chase her almost constantly) but then my little brother (he’s five) wanted me to win him some goldfish at the fair and we ended up leaving with SIX feeder fish, will my fantails lay eggs or will she be two stressed to lay them? and what will they look like so i can seperate the parents from the eggs??

  49. Your fantail will be fine. Eggs will be transparant circles and they’re tiny.

  50. Dear Friend,

    My Name is Nagaraj from India.

    I have been through your site and now I would like to ask few questions hoping that you will give me proper guidance.

    I have quiet a few Gold fish and sharks in separate tanks. Though they are doing fine, the only problem I face is their color.
    When I brought from a local store, their color was very bright (gold, orange, and black). But after a few weeks, their color started to fade.
    The Gold fishes whose colors were red and orange mixed with white, started to turn fully white. i.e., the gold and orange color started to fade.

    As far as maintenance is concerned, I change the water regularly and feed them properly. When I contacted the local stores for a suggestion, they try to
    reason with improper diet and make me buy different food they sell. Thinking that it may solve the problem, I tried many varieties of food but in vain.

    Kindly suggest me a proper remedy so as to bring back their color and to retain them.

    Thanking you in advance.



  51. goodday everyone: i have a goldfish in my home thru experiences i learned some remedies an technique regarding some of your problem which i loved to give an answer to your questions…1)separating the female fish alone without the male will not lay egg..the male is the one who’ll help the female to lay egg…2)after laying egg, remove right away the couple, they will eat the eggs…3)2-3 days after is the hatching…

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  53. Hi I have a small pond and my goldfish have produced babies but the majority are black will they change colour, the adult fish are ordinary goldfish

    regards Jan

  54. i have 7 gold fish and a filter but i want to know when are they going to have babies ans i also have guppies and one is fat does that mean it will have babies please help me

  55. what’s different between ranchu goldfish and lionhead goldfish?

  56. I have a 35-45 litre tank withe 1 fancy gold fish and 2 comets in it. I am going to get them a pond when they get to big but I need to know how big i should let them grow before I get the pond. Please help!

  57. Visit this website to find on the difference on ranchu goldfish and lion head goldfish:

    your views on this site.

  59. My pond is well a stablished for 5 yrs plus. Still no baby’s any reason why.

  60. My gold fish is alone since 7 months but todaythere are alot of small transparent balls in her bowl..they look like eggs but is it possible??

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  62. I have a goldfish all by herself in a small tank. I noticed she’s been swimming crazily back and forth for a couple of days now. Yesterday I went to clean out her tank and she had layed her eggs all over the bottom of the tank. I know they are eggs because I googled it. Im guessing they’re not any good without a male goldfish to fertilize the eggs but I didnt expect my fish to lay eggs especially without a mate..

  63. I have a female goldfish and it just laid eggs without the male goldfish that i had in a seperate tank. I did not know that goldfish was pregnant and when it laid eggs i helped the goldfish get most of its eggs out by massaging gently on its stomach near the anal.

    I was wondering how to take care of a goldfish after it laid eggs.

    I had another goldfish that laid eggs, but 1-3 months or weeks (I’m not sure) after laying eggs it died. The cause of death was floating at the surface of the fish tank, bloated, wouldn’t eat, and won’t swim properly.
    I don’t want another goldfish of mine to die…PLEASE HELP!!!!

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  65. i have a goldfish tank woth fancy goldfish and 2 carp. i was cleaning the tank today and i found a small orange gooey thing floating along the bottom i picked it out and put it in a glass when i look at it with my eyes it just looks orange but then i shone a light on it u can see like a really wierd shape inside it? what could it be. its lile a black shadow inside the orange stuff… its about 1cm x 1cm … totally confused

  66. I’m not sure exactly why but this blog is loading incredibly slow for me.
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  67. It’s really a nice and useful piece of info. I am
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  69. Hi! I just got 2 young fantail goldfish. As soon as i brought them home, one of them began chasing the other. I know that you cannot sex goldfish until they are fully matured… but I am truly confused. I don’t exactly want a ton of baby goldfish to deal with, considering these are the first goldfish I have ever owned.
    Aadvise would be appreciated, thanks!

  70. Hi my fancy gold fish are going thru the motions of breeding he is always chasing her nudging and nibbling at her rear end she is dropping lots of eggs but i dont think my male is producing any milt they have tried a few times and still nothing … so i researched how to manually help the gold (if thats the right word lol) she let out alot of eggs when i pressed her stomach but him nothing came out …. is this normal? Is it that he hasnt matured enough?, is it i am not doing it correct or do you think he will be producing milt ?

  71. how do you know if your fish is a boy or girl

    how can you tell if you’re girl having babies

  72. What I did is separate the female and male for a week and feed them plenty of live foods and foods with rich in protein. I just observe if the female tummy is swollen and soft before I place them together.

  73. My female fancy has been pregnant looking for a month now. She’s been lying on her side next to the filter intake at the bottom for a good three weeks. Is everything still ok, or what can be done. Is she going to die? How long can she go without food? I’ve had the two of them for @ six years and this is her first pregnancy. I do not have any plants, just two rock structures in a 20 gal tank.

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