Some misunderstandings when it comes to pregnancy, sexual organs and male/female ratio

I do read and hear a lot about when a pregnant female livebearer is due. Not that the replies at those forums ain't true but it's more that I do notice that it concerns generalizations.

Does every single female livebearer square off when she's due? No! When she will square off, it means that she took her max gestation period before she delivers. There is a large number of these females that are round shaped when they will deliver while the embryos are fully developed.

Overhere females that haven't squared off but gave gave birth within a couple of days after this picture has been taken.

Does every single female livebearer show a gravid spot (no matter the stage of pregnancy)? No! Most female livebearers (both ovoviviparous and viviparous) do show a gravid spot (when they're pregnant or non-pregnant). There are a number of livebearer species where the females won't show a gravid spot at all times. A "number" of limia species for instance. To most average livebearer keepers, these will be marked down as being rare livebearers. But to refer to a better known species; not even "all" female mollies will show a gravid spot. But again, there are more livebearer species where the females won't show a gravid spot. I haven't seen anybody overhere, saying this.

Overhere a molly female without a gravid spot.

Does a gravid spot "always" mean that a female livebearer is pregnant? No! The gravid spot is the most translucent part of the skin. Once it will stretch (when pregnancy hits in), this skin will become tighter and thinner which allows us to see the content. "Most" female livebearers show a gravid spot wether they're pregnant or not (with the exception of those species where the females won't show a gravid spot at all times).

Can females hold on to the eggs when they're almost due and don't give birth? Yes! This happens mostly when the female isn't feeling too comfortable in the tank. Can she absorb her embryos or unborn fry? Yes! If she's not able to drop her fry by any reason, she will be able to absorb them. This won't harm the female.

Does every female livebearer have the ability to store sperm packages? No! Sperm package storing is an ability that only refers to "most" (so, not all) female ovoviviparous livebearers. Certain strains that are superfetative don't always have the ability to store sperm packages. And viviparous livebearers don't have that ability either. Which means that a new mating is in order to establish a new fertilization.

And another note:
A lot of people don't know that the male's sexual organ is "only" called a gonopodium when it concerns an ovoviviparous livebearer. With the actual livebearers which are called viviparous livebearers, the male's sexual organ is called an andropodium. Both male sexual organs are also totally different shaped. Also the shape of the analfin of a female of both viviparous and ovoviviparous livebeares does differ. The analfin of a female viviparous livebearer is more round edged than of an ovoviviparous female.


And yes, also gonopodiums can not be compared with eachother when it concerns ovoviviparous livebearers. The shape of each species does differ which makes it complicated or even impossible to mate with a female of another species. The female sexual organ is compatible with the sexual organ of her own kind. Only those species which are closely related "can" establish a "possible" mating if the sexual organs are compatible till a certain degree. Even when it looks like it that a male has been chasing a female of another kind the whole day, if the sexual organs ain't compatible no actual mating will take place.

Overhere a summary how different gonopodiums may look like.


Even if you'd enlarge photos of gonopodiums, you'll see more differences in shape (this following photo is taken from the internet).

These are just examples of how different they can be. There are way more different kinds of gonopodium shapes when it comes to ovoviviparous livebearers.

When a colony or group of livebearers is kept in a tank and there's a pecking order... Is it always that the dominant males will father the offspring of the females within the colony? No! In general it would be correct. But there are also the socalled "sneaky males" Those sneaky males can be submissive or smaller males. Most of the time when an alpha male will chase a submissive or smaller male away, other non dominant males will have the chance to use that opportunity to try to mate with a female.
But it's the female which allows a male to mate with her or not. Eventhough males can be persistant to mate, it's the female which decides if a mating will take place or not. Unless, it's a very young and naive female.

Does every adult livebearer eat their fry? No! it really depends on the species wether the fry will be left alone or not. So, saying that every adult livebearer will eat fry as long as it fits in their mouth is an incorrect remark. But yes, a large number of livebearers do like to hunt their fry. But there is seriously a decent number of livebearer species that will leave their fry alone.

About a pregnant female boxing off or squaring off:
Overhere, I do have a female Poecilia vandepolli ( a wild molly from the Dutch Antilles) which does have a boxy build. But she's not pregnant. Just healthy and well fed.
But again, when an average livebearer female squares off, she's used her max gestation period. But that's why I've been mentioning that not all livebearer females will square off when they're due. The topic that I've written overhere is referring to the generalizations that I read a lot at forums. A lot of general information found on the internet are copied texts from commercial books. There is specified information to be found which does reflect the truth about livebearers. But you really have to search selectively.

Another generalization about livebearers is to keep a male/female ratio of 1m/2f or 1m/3f at all times. As being a true livebearer nerd (to use that word for once) I do know that that ain't true. For not all livebearer males (depending on the species) wil harass females. Which makes it possible to keep certain livebearers at a ratio 1m/1f without any problems. It's also the size of the tank that will encourage the harass issues. Or better put: The open space left in a tank ( for also bigger tanks can be really stuffed with plants, rocks, wood or decorations) will influence their behavior as well.
But overhere, with most livebearer tanks I really don't have a ratio that involves more females than males. And if you'd live closer to me, you could see it for yourselves that it's not an issue at all.

And if someone wants to buy an aquariumbook, I'd recommend to buy an old one and not a commercial one that's full of generalizations. A new commerical book (most of them.. so, not all) may look nice with all those high definition photos and pictures but older books (preferably from before mid 1980's) do contain more valuable information.

I hope this gives more insight of how it works with livebearers.
And sorry for the long story...

Great information. Do you also have any egg layer info like for tetras? I just had a tetra fry show up in my tank and didn't have a clue it was coming.

Retired Viking said:

Great information. Do you also have any egg layer info like for tetras? I just had a tetra fry show up in my tank and didn't have a clue it was coming.

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Well, I've kept a lot of egg layers as well. But my main focus are livebearers.
Tetras prefer to lay there eggs in the dark on plants. Or at least on a spot that doesn't have too much light in the tank. Probably, they've laid their eggs at such a spot in your tank. Once they've laid their eggs and the male has sprayed his sperm over the eggs, the eggs will hatch in about 4-6 days (depending on the water temperature). After hatching it will also take about 1-3 days before the larvae will swim freely. And it's quite funny to see a needle turn into a small fish.

emeraldking said:

Well, I've kept a lot of egg layers as well. But my main focus are livebearers.
Tetras prefer to lay there eggs in the dark on plants. Or at least on a spot that doesn't have too much light in the tank. Probably, they've laid their eggs at such a spot in your tank. Once they've laid their eggs and the male has sprayed his sperm over the eggs, the eggs will hatch in about 4-6 days (depending on the water temperature). After hatching it will also take about 1-3 days before the larvae will swim freely. And it's quite funny to see a needle turn into a small fish.

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The fry I have looks to be just over 1/4 inch and was free of any egg sack and swimming near the surface when I 1st saw him. My guess he is a red eye tetra but I didn't get a good look at him, so he may be over a week old.

I wish I would have had this info to help me when I decided to breed black mollies and African Cichlids, Back then we didn't have the internet. I needed help because the cichlids took over my 55 gallon tank and mollies my 20 gallon tank. I was doing it for fun not profit but I guess I over did it. I gave away so many fish to friends and anyone who wanted them. Sorry for hijacking your post with the tetra question.

I'm not particularly well-educated about live-bearing species but I did find your post very interesting. But I think I (and a number of others) might appreciate a little dictionary of some of the more complex terms you use in your post - otherwise it may be a little intimidating to some people. For example - what is "squaring off"? Is this a behavior exclusive to livebearers (I have a cherry barb I think is carrying eggs but can't find a safe place to lay them) - do they "square off" (whatever that means). I understand some (but not all) of the other vocabulary you use but others may not so you may want to write a dumbed down version of your very good post. Just a suggestion - it's a little intimidating to read and of course, what the purpose is, is to communicate in the easiest way possible.

You obviously have amazing knowledge about live bearers. After reading this, I would actually consider a tank of them if I didn't worry about over-population. I don't know anybody other than my daughter that is "into" fish and she only keeps a small tank at work for her co-workers (and her) entertainment. But they are all males because she didn't want to risk breeding and having no place to put the fry. What do you do with over-population once you run out of friends willing to take the babies? Do you just allow nature to take it's course and have the parents or other fish eat the fry?

A sort of funny/horrible story - when I was about 4 yrs old my mother bought me a fishbowl with a couple of guppies, turned out they were a male and a female and the female gave birth to what looked like hundreds of little fry and both parents began eating them. I'm freaking out watching this horrific site while my mother is desperately trying to find another bowl to put the fry or the parents in. She got so rattled, she spilled the entire bowl on the floor so we had mom and dad flopping about and a lot of dying fry. The trauma was just too much for both of us (I think she was able to save the male guppy but all others died.) I still have a very vivid memory of this incident and I swear that's what keeps me from getting involved in livebearers. Maybe I'm over-reacting but I was a VERY sensitive little girl.

I recently watched a local fish store accept money from customers to watch them feed their piranha live fish. Three little boys watched this, the oldest one thinking it was "cool", the middle child, just kept quiet while their little four year old was screaming and crying telling the baby fish to "keep hiding" only to watch them poke their heads out and get eaten. I realize this is what piranha do, but it was absolutely horrific to watch. Not to mention the tank with the piranha had no warning sign or cover on it - I myself almost tried to "pet" one of them that seemed so "friendly" only to be warned at the last minute what they were. Totally irresponsible and sickening to accept pay to watch a slaughter - I'll never return to that "mom and pop" fish store again.

I just can't stand the thought of fish eating other fish, I understand the reality of the world but I'm a bit of a wuss hence my reluctance to have any live bearing fish.

Oh and your photos are truly amazing - I mean that sincerely. But do we call this fish porn? (just kidding).

Jan Cavalieri said:

I'm not particularly well-educated about live-bearing species but I did find your post very interesting. But I think I (and a number of others) might appreciate a little dictionary of some of the more complex terms you use in your post - otherwise it may be a little intimidating to some people. For example - what is "squaring off"? Is this a behavior exclusive to livebearers (I have a cherry barb I think is carrying eggs but can't find a safe place to lay them) - do they "square off" (whatever that means). I understand some (but not all) of the other vocabulary you use but others may not so you may want to write a dumbed down version of your very good post. Just a suggestion - it's a little intimidating to read and of course, what the purpose is, is to communicate in the easiest way possible.

You obviously have amazing knowledge about live bearers. After reading this, I would actually consider a tank of them if I didn't worry about over-population. I don't know anybody other than my daughter that is "into" fish and she only keeps a small tank at work for her co-workers (and her) entertainment. But they are all males because she didn't want to risk breeding and having no place to put the fry. What do you do with over-population once you run out of friends willing to take the babies? Do you just allow nature to take it's course and have the parents or other fish eat the fry?

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Sorry, I wasn´t aware of it while posting this that certain terms might be unclear. My apologies...
I'm used to write in a certain way. For I do write articles for a dutch, german and once for a french livebearer magazine. But yes, it might be a good thing for me to try to write in an easier way.

Squaring off:
When a pregnant is almost due, she may have a big belly. It can be round or boxed shaped. A round belly is like the picture I've showed before. Like the picture below.
Very pregnant but a round shaped belly.

When it's boxed shaped, it's called squared off. Just like the picture below.


Just to make certain things clear, I've paste a partial text from my own website overhere:

In general fish are wether oviparous or viviparous. When fish are oviparous, the females will spawn the eggs. The fertilization can happen internal (true oviparity) or external (ovuliparity).

When it comes to livebearers, they won't lay eggs (oviparous) but have embryonic development within the mother after an internal fertilization. And when the female is due, she'll give birth to free swimming offspring.

To most people, livebearers are all alike when it comes to reproduction. But that ain't correct for there are two ways how these kinds of fish reproduce. Most known are the ovoviviparous livebearers like e.g., mollies, guppies, swordtails, platies and so on... But there are also the true livebearers like e.g., goodeids (splitfins). These true livebearers do have a reproduction which is pretty similar to mammals.

True viviparous livebearers like goodeids in the embryonic state are being nourished by the mother through the socalled trophotaenia (or also spelled as trophotaeniae). It's in some way similar to the umbilical cord (placental viviparity) in mammals. These trophotaenia will be shed or absorbed (they'll nourish themselves through the trophotaenia) in the first till two days after birth. These trophotaenia do look like a cluster of small umbilical cords.

With ovoviviparous livebearers, the embryos have no placental attachment and will be totally nourished from the yolk sac. So, the mother does not nourish the embryos, she's just a safe place before the eggs will hatch. By the time that the mother is ready to give birth, the eggs hatch and the fry will pop out of the female's body. Mostly they're curled up when they leave the mother's body. But sometimes when it takes a bit longer before fry can leave the mother's body, the rear end of the fry will come out first.
The fry do have a big belly. They'll nourish themselves the first till two days after birth with what they've stored in their belly. And than they'll slim down and than they'll look for food themselves.