Determining Male & Female Guppies as They Mature

Besides some rambling I explain the things I look for in young guppies as they grow out to determine males from females at a young age. Some strains the sexes can be determined at roughly 6 to 8 weeks. Other strains take more time to develop differences in shape or color and it can take 3 months.
It’s very important to separate males that start to develop and grow them out in a separate tank from the females so you can select your breeders as the fish mature and you can see the colors and finnage you are looking for.
If you are colony breeding you want to remove the males that are not up to par, such as smaller fish, color imperfections or deformed body. I’ve tried to show fish from Red Deltas, H/B AOC’s, All Red Albino And Platinum Red Mosaic Big Ear Guppies as these strains have some differences.

[@LiSa.N.J]

I do the gravid spot too...been pretty accurate on finding the absence of a gravid spot being males before they go "pointy" This has worked pretty good for me so far. Great info and video.

[@DGrey]

Thanks very much! It all works well until you get that 1 fish that switches sexes 3 or 4 months in. They usually don't live that long though.

[@LiSa.N.J]

@@DGrey I guess with all the years and experience you have growing out fry, you've seen this happen many times, I have yet to have this happen that I can recall. I do look for the pointy male part most times tho.

[@DGrey]

I've seen it a few times. Probably has more to do with raising specialized strains vs larger genepool guppies.

[@MobbGuppy]

Really enjoyed both videos today. I am amazed by the dark black in that young Half Black AOC male. Striking.

[@DGrey]

Thanks very much Peter!

[@sasop.9417]

Very nice and informative video.

[@DGrey]

Thanks very much! I appreciate you watching!

[@otcfishkeeper5414]

Great info, thanks.

[@DGrey]

You are welcome! Thanks for watching!

[@BecauseYourFish]

Nice, thank you!

[@DGrey]

Thank you for watching!

[@jennynunn333]

I have a question.. on female guppies, after giving birth, the area of the gravid spot turns orange like jello. I once read this means the female is no longer bred, Once all sperm from all mating is used up, she will not breed back again. Is this a fact, that the orange gravid area means that fish is barren ?

[@DGrey]

Thank you for watching! The lighter gravid area can be new eggs forming to develop in their body or even poop. I will use a female for a cross after she had fry because they are more apt to accept the sperm from the new male. They can store sperm for up to 4 or 5 months. I had a female that had fry 4 more times after the male she was in with died. I did a video on that a while back.

[@jennynunn333]

i hope she is making new eggs. she is new and young, I paid serious money to get her shipped, Green Moscow, and she had this one batch of fry about 2 weeks after she arrived. I am doing my best to raise the fry, but I want her to breed back. today I put her with a cross as you suggested... I hope that works. I wish I knew more about the mating behavior patterns. For one thing how long can she go without mating, or how soon do the females breed back after the fry are born ?

[@jyajaquaroom8039]

If I can't tell my guppies is a female or male I'll look at their colors. The most colorful will be the male and least colors will female. It's seem like male colors up faster

[@DGrey]

Thank you very much! I like it!

[@guppybreeder9147]

dude i have a strain called albino german yellow, it is very similar to your albino snow white. i dont think they have difference at all, they are exactly identical.

[@DGrey]

Thanks for watching! I had that strain years ago and really liked it. These are white but could be realted since I've had a few that get yellow in the tail.

[@PerplexiaX]

Okay, so... I know basically it's coloration and size in how you can tell the difference between male/female, but at what age can they start breeding? My first brood is about five weeks old now (born July 21st), I'm not sure which mix they are yet, probably a regular wild mother and a Turquoise father, and I need to separate the sexes before they start... getting ideas! lol

[@DGrey]

It probably will depend on the strain but I think once the male's gonopodium is fully formed they can impregnate the females. You are probably looking at 8 weeks for most strains. If I were to line breed the fish I showed I would pull out the males as the anal fin gets pointed and put those fish in a separate tank. Then select the best males to put in to a tank with the best females.

[@PerplexiaX]

@@DGrey Right, if I was doing this as a business, but as I've mentioned before, I'm not concerned about breeding for profit, just playing with it! ...and I can't afford to buy and run that many tanks! LOL I am noticing more color now, definitely a yellow tinge in the tail with a dark spot at the point where the tail begins, so if the mother IS the regular wild, the father could be the yellow male I have... it IS kind of fun wondering exactly who the parents are, trying to figure it out, but at the same time, it would be nice to KNOW! I see you have a part 2 of this... I'll go check it out! :-)

[@ReneesZooTube]

@@PerplexiaX One thing that's interesting is how the coloration on guppies develops. Certain color cells develop before other color cells. I can't remember which is which, but I know the Yellow color cells and red color cells develop at different times. So you can often see the colors change a bit as the guppies grow. 😊

[@PerplexiaX]

@@ReneesZooTube Yeah, the lower part of the body going towards the tail fin on one of them was pretty dark for a moment, then a moment later when I looked again, I couldn't tell which one it was... it could have been the way the LED light was hitting it, it could have been right under one of the blue lights. I got this one... it's multi-colored: www.amazon.com/Aquaneat-Aquarium-Spectrum-Multi-Color-Marine/dp/B07G91RKC7/ref=sr_1_23?keywords=aquarium+led&qid=1567189603&s=gateway&sr=8-23 I just want to make sure I get them separated before they mate! Bro and sis mating is a bad idea, I'm assuming?

[@ReneesZooTube]

@@PerplexiaX actually, not necessarily. Breeding siblings tends to be the staple method of many Guppy breeding programs. And I know of st least one study showing no degeneration after I think 40+ generations of inbreeding in a closed population. But it also depends on the genetics you start out with too. Weak fish bred to any fish will produce weak fish. But it likely won't be the end of the world if your guppies mate with each other. Especially as the parents sound like they're not closely related.

[@sativaknight9358]

my red grass males always colour up up late they get meesed up borders on the caudaul an then out of nowhere they look good haha what weirds me out i keep getting japan blue males that'll mature quicker too an colour up almost way before my red grass they dont have a bandit marking like a nike swoosh either just a dot

[@DGrey]

The red grass and blue grass lines seem to devolve in a few generations. They probably need a related cross to get the fine grass pattern back in the tail and the nike mark on the side. I don't know what to cross them with. I think maybe it's best to run 2 separate lines of them and cross some of them in to each other once grass pattern gets larger.

[@klove7365]

Thank you for educating the public 😀

[@DGrey]

Thanks very much!!

[@kens_fins8764]

For some reason my females grow faster than my males. Because of the growth rate differences, I've been able to seprate them by size so far. Usually once seperated the males start growing at a good rate and catch up to the females. It's been this way with every batch.

[@DGrey]

That's great. Makes it easy to figure out who is who. It could be the strain or things are just working out very well for you. The all red albino's in that video have now grown enough to tell males from females easily.

[@kens_fins8764]

@@DGrey I'm thinking that it could be the strain of half black reds I got. I set up two seperate colonies apart from my line breeding to test that awhile back and they all do the same.

[@kens_fins8764]

@@DGrey I'm trying to find a way to make the reds show through better in my half black reds, I've been searching through your videos because I know you have mentioned it before. I just can't seem to find that video.

[@DGrey]

You have to cross in a gold bodied red male once the black or mahogany color starts showing up in half black reds. I think it's the toughest strain to raise. I had bought them directly from Stan Shubel years ago and couldn't keep them going.

[@DGrey]

That's really cool though. Some lines do mature faster. The slowest I have ever seen in my life are these platinum red mosaic big ear guppies.

[@highwateraquatics2476]

Woman seem to go for the bad boys.🤣

[@DGrey]

That's the truth!! :)

[@HadleyCapeBreton]

got to love guppie puberty lol

[@DGrey]

Thanks very much! I had to be careful how I worded the title. I wanted to call it sexing young guppies but I figured youtube wouldn't like a title with sexing in it. :)

[@HadleyCapeBreton]

I'm breeding tequila sun rise guppies and half black Moscows so I know the pain

[@DGrey]

They sound good. I think the tequila sunrise lines are closely related to yellow deltas. Something to do with doses of the platinum gene. I have zero retention on the actual genetics just like sometimes I can only remember the punchlines to jokes and not the whole joke!

[@bgd73]

I look for appetite. the female is a beast...from day one. I have also seen newborns nestling the side of moms belly..as if playing that is male, within 1 hour. But, best to wait, they change.. that is freaky. No worse than tiny splenden female bettas.

[@DGrey]

Thank you for watching! You could feed guppies 15 times a day and they's eat the food until their stomachs exploded! Stuffing them with good quality food is a great at way to get them to develop faster.

[@inavthakur]

At what age anal fin start to get sharpen?

[@DGrey]

Thank you for watching! Usually between 8 to 10 weeks. Some strains seem to take a bit longer. With fry sometimes you will notice males will start coloring up before the gonopodium develops.

[@libbypearce7875]

Why are you saying the you get ugly fish when it's well known that guppies of some of the most beautiful and easy to keep fish also if you knew anything about fish especially guppies you would know that they don't always reproduce fish that copy that own Finn patterns

[@DGrey]

Thanks for watching LIbby! I was being sarcastic when I said ugly fish:)

[@ChattanoogaEd]

Thank you so much for all this great information. I'm just getting in to guppy's now so hopefully someday I'll be able to use some of your awesome knowledge.

[@DGrey]

Thank you Ed!!

[@GUYANAAAAAAAAAAAAAAA]

Do yo hAve a way to contact you ?

[@DGrey]

Hi Rico, greydmail at yahoo.com

[@ibrahimfazeel3951]

My guppy gave birth to 73 babies 😊🥰

[@DGrey]

That is amazing! Congratulations! More tanks!

[@PrancingToad]

Thanks so much for this video! I’ve been keeping guppies for almost 3 years and I’m pretty good at telling what sex they are, until this drop of Full Golds. It’s a drop of 28, I couldn’t believe myself when most of them were getting a sharper anal fin. I thought I was losing my eye, but this video helped confirm that 25 of them are developing into males. I can usually tell when they hit about a month and a half for this strain specifically, but this drop has puzzled me for over a month and I’ve been at the edge of my seat looking at them for what feels like hours a day just to figure out if what I’m seeing is real. The remaining 3, I’m hoping they actually develop into acceptable females. This is the first time this wide of a ratio has happened to me and the prior drop females weren’t up to my standards. Thanks again!

[@DGrey]

You are welcome and thank you for the kind words! Yes I have also done crosses where I ended up with all males or all females. Very frustrating. It could be that the female was older and just not as fertile as before. I've heard it referred to as the death gene, meaning the line can't continue with only 1 sex.

[@PrancingToad]

D Grey I’ve heard of that, it’s one of those things you don’t think would happen to you until it happens. 😢 She’s around 4 months old, but I just sexed the drop from her sister (I acquired her virgin from the same breeder later on who decided to switch to bettas, so I got a batch on discount) and she had 17 females and 14 males in this drop. I might have just been unlucky, but the original female’s 2nd drop is coming of age. If they’re turning out to be mostly males again, I might just retire her early. Thanks for reading and and taking the time to respond to me! ☺️

[@jeannieb4554]

No fish are Ugly.

[@DGrey]

Thanks for watching! Good point!

[@jeannieb4554]

@@DGrey Thank you for posting the Video.

[@DGrey]

You are welcome! Thanks again for watching and listening to my bad jokes when I toss them in there.

[@sativaknight9358]

ever seen a one eyed goldfish with the googlie eyes?

[@DGrey]

Sounds like the start of a great joke! :)

[@madfishdiva]

Very interesting. I never realized how similar the males and females are at this age and size.

[@DGrey]

Thank you!! The changes in the fish do happen quickly after they start to mature.

[@ReneesZooTube]

Excellent information! I look for gravid spots vs. "going pointy." Also the absence of a gravid spot can be telling before the males start to "go pointy." Sometimes you can compare that area between siblings and get a pretty good idea of who is going to be male when they aren't showing the gravid spots their sisters are. If you know what to look for and you know your line a bit, you can get pretty good at seeing when the males are starting to "go pointy." 😊 I've got my first batch of Panda Guppies starting to "show" at about 3 months old now. I'm seeing some males starting to go pointy and female gravid spots. It's my first batch of this type of Guppy maturing, so I'm also watching how the colors develop on the males vs. females as well. I'm doing colony breeding with them, but I'm leaving in all these first males right now. I'd only gotten a pair initially, so I want to make sure I've got more males and females. I'm going to start culling later, and with batches 2 and 3 that are currently growing out. I also just moved one of the Pingu female juveniles (from the adults I got from you) to the Panda colony for a much anticipated cross. She's only about a month old but I can see her gravid spot already. The adult Pink Pingu females I got from you just had their second batches of fry this past week. 😊💖

[@DGrey]

That's great about the pandas and pingus congrats!! I hope things keep going great! Wow if I only knew of the "pointy" reference I would have named the video pointy and non pointy guppies!!

[@ReneesZooTube]

@@DGrey 😆😆

[@mrh2132]

Hi everyone If you want to get nice colors in guppies just food them spirulina and watch all very nice colors

[@DGrey]

Thanks for watching and great tip! Yes spirulina is great for guppies. I've been told that overfeeding it is bad and can damage their organs, so don't overdo it.

[@nycstunnerinc8556]

Love your video I have a question my female keeps get pregnant with out a mate she dropped fry 3 times already I only keep her with tetras how is that possible

[@DGrey]

Thanks very much! The females can and do store sperm (from the last male that impregnated them ) in their reproductive system somehow. I think you are at the max now. 3 more drops is the most I've heard of and you are lucky!

[@nycstunnerinc8556]

Thanks for the info I believe she’s pregnant again so the 4 drop is coming omg to many guppy fry

[@DGrey]

Enjoy the guppies! You have a great producing female!

[@michaela-be4le]

Good morning Doug....helpful content indeed :) I usually sex my fry at 3 to 4 weeks depending upon the specific strain. I look for the same ques as you do together with looking for the iridescence that occurs on males on the upper half of the body; this is best viewed when held on their side while netted. I typically sex up to 1000 fry per week, so I kinda got good at it :) What I've also noticed is that the anal fin in females is a more rounded triangle whereas in the males it's a sharper triangle even before developing a gonopodium. Also females show a much clearer separation of the intestine and stomach wall in the coelomic ( pronounced cole lomic ) region, which ends just before the vent in a tiny half circle. Hope this helps; but I'll be honest....I need to use a 200 magnification pair of eye glasses :)

[@DGrey]

Wow Michael that is fantastic! Thank you! I'll try but my eyes lately are as blurry as that camera lens was as I tried to focus on specific fish! I wanted to show a tank of young snow shite albinos but they sex out really quickly and the sexes of the ones from May are already extremely visible and the fish from the late June batches are starting. I may do a fast extra video on the 2 tanks of them tomorrow.

[@michaela-be4le]

Lol...you are so welcome :)

[@Wal48]

michael a I’ve noticed that about the anal fin triangle too, definitely slight curve in the female and straighter in the male. Wish I had younger eyes though, or the fish would stop whizzing around!

[@PerplexiaX]

Would you please look at my comment above (or below) and respond ... I'd like your take on it! Thank you! :-)

[@michaela-be4le]

@@PerplexiaX Having been bred and hybridized for so many years, guppy fry's sexual maturity can vary from as early as 4 weeks old to as much as 6 weeks and old. I have a yellow strain that I developed about 5yrs ago, and both sexes are mature by 5 weeks. My red flamingos have bred at 28 -30 days old I'm guessing, as the spawn appeared when they were 58 days old. ( I'm assuming that courting may have taken a day or two ) The female then died after birthing 33 fry. My red Dumbo ear mosaics mature at 6 wks. Hope this helped :)

[@thestruggler1000]

Thank you Doug. That was an extremely good video.i am disabled and have one ten gallon tank. The guppies keep breeding. Could you please tell me if when the tank becomes really crowded do they stop to sort of control their population. I live in Northern Ireland and do not think my local fish store take fish from the public. Thanks for taking the time to read this. By the way I just wanted to have a nice variety, and are not fussy about types. 👍

[@DGrey]

Thanks very much! Sorry about the disability, life throws us some curves. They keep breeding and breeding and breeding. You may have to get a big cichlid or a piranha in another tank!

[@ReneesZooTube]

They also do often eat their own fry, which can help a bit. You might want to ask your local fish store if they'll take some guppies from you. So will. Sometimes they'll even give you a bit of store credit in trade.

[@thestruggler1000]

Thanks Doug but we only have the one tank now, as I am only barely able for that one. But I appreciate you responding to me, it was kind. 👍

[@thestruggler1000]

Thanks Doug but we only have the one tank now, as I am only barely able for that one. But I appreciate you responding to me, it was kind. 👍

[@DGrey]

Just do the best you can and enjoy what you have. Your 1 tank is probably Way cleaner than all my tanks so there's that :)