European aquarists were first intoroduced to livebearers around 1890. With the exciting discovery that these fish gave birth to live young, live-bearers quickly became VERY popular. Very high demand resulted in big prices. Luckily, live-bearers reproduced well in aquariums( as we all know) , and the prices soon dropped. The rarer species weren't imported until the 1960s.
Intro to Fish Families
There are primarily 4 families of live-bearers that are of interest.
Live-bearing Toothed Carps (Poeciliidae) make up the largest family, with almost 200 species! They are called toothed carps because they have teeth on both the upper and lower jaw. The teeth are so tiny, though, that you need a microscope to see them. Toothed carps are usually kept in aquariums. Some popular memebers of this family are: Pike Live-bearers, Mosquito fish, Yellow bellies, Metallic live-bearers, Midget live-bearers, Limias, Merry Widows, Guppies, Mollies, Swordtails, and Platies.
Mexican topminnows ( Goodeidae) These fish aren't commonly found in tanks. Only about 35 species of this live-bearer are known.
Live-bearing halfbeaks (Hemirhamphidae) are easily distingushed from other live-bearers by their their beak-like mouths,and straight pike-like bodies About 20 species are in this family.
Four-eyed fish (Anablepidae), the fourth family, are some of the most interesting fish you can keep. They have the amazing ability to see above and below water at the same time, thus the name four-eyed fish.
Where They Come From
Live-bearers are only found in the wild on three continents: South America, North America, and Asia.
Live-bearing toothed carps originally came from the Americas. Their range extended from the North USA, to Argentina, in the south. These fish feed primarily on mosquitos and their larvae, however, scientists conceived the idea of using them to control the mosquito population biologically. Guppies and mosquito fish were introduced into the wild and swampy areas of Southeast Asia and the Philippines to keep marial mosquitos in check. The fish spread to all sub-tropical, and tropical waters, including the waters near southern Europe.
Mexican topminnows live in the rivers and lakes surrounding, and in the Mexican plateau. They also live in the rivers leading down to the Pacific ocean, from the plateau.
Halfbeaks live in both fresh and brackish water. They can be found from in India to Indonesia, also in the Philippenes and Southeast Asia.
Four-eyed fish generally live the in brackish water of mangrove swamps. They occansionally occur in pure saltwater too. These fish have been found living in freshwater, hundreds of miles inland, but they are usually found along the Atlantic coasts of Central and South America.
Is it Healthy?
Before buying any fish, you should inspect it closely. From an animal's external apperance, you can detect many problems and diseases. Particulary examine the body, gills, fins, eyes and skin.
Body: Any healthy live-bearer's abdomen should look convex, when viewed in a profile. The female usually looks more convex then the male. These fish have a "chubby" look to them. This should also appear in females that have just given birth, even though they may look very slender. All other fish should appear well-fed.
Be careful of fish with protuding scales, and bloated bellies! Most times, if not all times, these fish are incurable.
A large head, that looks disproportionate to it's body, is usually a sign the fish has undergone long hunger periods. This doesn't mean the fish will die, but it shouldn't be used for breeding.
Gills: Healthy fish breathe slowly, although they breathe somewhat faster in a densely populated tank. As the fish breathe, they expose the gill cover. This should appear a pale reddish color, in healthy fish.
Fins: Missing or partially developed fins are ALWAYS a bad signal. Frayed edges on the fin, are usually the sign of a disease, although there may be other causes.
In a healthy fish, the fins should visably stick out from the body. The one exception is the dorsal fin in some species.
A fish that clamps it's fins, and maybe rocks from side to side is definatly not feeling well, and may easily get a disease.
Eyes: The eyes should appear clear, and never protrude un-natuarally from the head.
Skin: The skin should not show any white spots, mold, fungus, or white film. The scales should hug the body, and look smooth. Be sure to examine the tip of the mouth with extra care, to be sure there is no white film.
Another sign to look out for when buying healthy fish is avoid it if it seems to hang around on its own near the bottom of the tank alot as this is a common sign of a sick fish. Also avoid getting a female livebearer that is heavily pregnant(although this can be hard to find, particurally in guppys) because not only is the move from the fish shop to your tank twice as stressful (i.e she will be more likely to abort her fry, become ill and/or die). The other reason is if there is a sudden difference in water stats like ammonia in coming from the lfs tank water to yours, this can cause birth deformitys in the fry, cause still born fry and/or miscarriages.
How Many Should You Buy?
Most livebearers are shoaling fish, so you should always buy at least 2, preferably several fish. A shoal consists of at least 5-6 fish. There should be more females then males.(general rule is 1 male to 2-3 females)
In the case of swordtails, the ratio should be changed, because the males are highly agressive towards each other. Buy a small shoal of about 5-7 fish, which includes only 1 male.
You should only buy live-bearers singly if you get a pregnant female, and plain to build up your strain with the offspring.
Make sure they fish you buy are about the same size, to limit agression. Also, young females can suffer with larger males going after them.
Species or Community tank?
As the name suggests, a species tanks holds only 1 kind of fish, such as guppies. A community tank will hold an assortment of fish, as long as they are compatible. A community can hold just different types of live-bearers, or live-bearers and a few other compatible fish, such as cories, tetras, rasboras, barbs, other catfish, and a few small cichlids.
Community: Most types of live-bearers will act natural, and be happy in a community tank. Some species can be bred in community tanks.
Species: Only a few types of live-bearers need a species tank, such as the Girardinus falcatus, or Yellow belly. A species tank can be useful, if you are keeping small or delicate fish, or if you are keeping large fish, like pike live-bearers. It can also be useful if you want to do selective breeding, because you can check on the fish at any time.
Most every fish owner and hobbyist knows the lyre-tail guppy. Fish with such ornamental, and extravagant tails don't occur in nature: they are reached through careful breeding, by humans. This is known as selective breeding. Three critera are important in the fish to be used for seletive breeding of ornamental fish: fin shape, color, and body shape. You should have your goal set, before you begin to breed.
Which Live-bearers are Suitable?
Not all fish species are suitable for selective breeding. The most promising candidates, are fish in which deviations from the normal form, occur in nature. In English, it means the fish already have some variety in fin shape, color, and body shape. Other types of fish require hundreds of generations, before the littlest thing will change. In live-bearers, this can be accomplished in a few generations.
Seven species of live-bearers belonging to 2 generas, are most suitable. They are the guppy (Poecilia reticulata), the molly ( P. sphenops, P. latipinna and P. velifera), the swordtail (Xiphophorus helleri), and the platy (X. maculatus and X varitus).
In some fish, inbreeding can be a real problem. This, thank goodness, is generally not the case in live-bearers. In fact, for some selective breeding, it is necesarry to resort to inbreeding, to get the trait you want. Nevertheless, you should always watch the fry you raise closely for signs of inbreeding, especially if they have mated only with closely related fish for more then three generations.
Possible signs of inbreeding are:
- Physical malformations, such as bent spines or misshapen heads
- The offspring are lacking numbers, even thought the fish are kept in optimal conditions.
- More then 10% of the fry are dead at birth
- The number of young is consistently lacking (although this can be caused by other other things too)
- The fry fail to get as big as their parents, in spite of feeding and optimal conditions
- Almost all the fish die young, before reaching maturity.
So. You have a pregnant livebearer. Let's say she is a guppy (as all common lievbearers have pretty much the same pregnancy regime) and she's been in your tank for just over 3 weeks with a male guppy too. The chances are that she got mated with in the first couple of days of arrival as guppies have very high sex drives and it is very likely she would have done so.
During her pregnancy you may have noticed various changes in her behavior in the 3 weeks she's been pregnant, to begin with in the first week there aren't many changes. Perhaps she gets harrassed by the male a little more and she becomes a bit more intolerant of other fish.
In the second week you will notice an increased appetite, the first signs of the gravid spot and a slight increase in weight; the "gravid spot" is a dark patch seen and located towards the back of the pregnant females tummy and appears as a dark/black spot. This spot is actually the frys' eyes you are seeing which as they develop, become darker and darker and take the appearance of the gravid spot on the outside of the pregnant fish at the back of tummy where the skin is thinner.
Many people use this "gravid spot" to indentify whether a fish is pregnant or not although not all livebearers show this depending on their color.
In the 3rd week the gravid spot will have become very dark and her tummy will look so pregnant like it is going to pop. Her appetite will have increased more and she will be more competitive with other fish for food and intolerant of them; she will be spending more and more time by herself around planted areas in the tank or where ever there are hiding places available. She can give birth in the 3rd week if she is expecting just a few fry but most guppys take about 4 weeks; mollys and swordtails can take up to 2-3 months if they are expecting a large amount of fry.
Common livebearers can produce anywhere between 5 and 100 fry although for the most part they don't exceed 20. You will generally find the larger batchs of fry coming from mollys and swordtails (i.e 50+ fry) due to their larger size and pregnancy times in comparison to platies and guppies.
The 4th week you should be expect the fry although the pregnant guppy can take up to 5 weeks if she's expecting many fry or she doesn't feel water conditions are good enough for her (livebearers can hold onto fry if they feel their enviromental conditions aren't suitable. Also if they have unfertilized in them for periods of time they may abort them or somtimes eat them for nutrition.). She can also abort the fry if she experiences alot of enviromental stress or doesn't get enough food/nutrition.
There isn't much you can do to ensure she gives birth except raise tank temp (it is advised you don't raise it higher then 26 C), and feed her a varied nutirious diet and keep water quality conditions top notch to help encourage her.
The fry birth process can take up to a day or more and she may even just give birth to a few fry and then deliver the rest a week later. During this time it is best not to disturb her and many people move their pregnant livebearers to a breeding tank or net/trap a couple of days before she is expected to give birth so she isn't harrassed by other fish.
When the fry are born they may not eat for up to 2 days although it is best you start feeding them from day one as this varies alot with fry and they can eat anywhere between this time and day one.
Some fry never get to grips with this new world; in some cases their lungs/swim bladders do not fill up with enough air when they are born thus causing them to have swimming problems and they appear to hug the bottom of the tank all the time- these fry are often called belly-huggers and should be put down ASAP as they never live long and find difficulty from eating and often suffer swim bladder disorders.
The best place to raise your fry is a spare "fry tank" although breeding nets are acceptable too if you don't have many(20-) although even so they will soon outgrow the breeding net. We will talk about both here...
A fry tank is simply a spare cycled tank with adequete heating and filtration and/or lighting and planting and either has no other fish in it or fish that do not eat fry( i.e panda corys). I would say the advised size fry tank is 10 gallons although if you can get bigger, the bigger the better (although i wouldn't suggest more than 30 gals as it will become very difficult to monitor how many fry there are or retrieve and dead ones/spot unwell ones).
Fry tanks are better than breeding nets especially because they can offer more space for the fry and people have said that there are much higher survival rates in large batchs of fry.
My only concern with fry tanks is that the water stats should be as near as posible to the tank they came from as so to help prevent fry dying from stress/shock- it is not wise to move fry around too much especially in the 3 months old and younger stages of life.
Breeding nets are quite controversal and in the scenario of moving the pregnant fish before fry birth I think it depends more on the scenario the pregnant fish is in.
When a pregnant fish gives birth she releases scents into the water which other fish will/may smell and harrass her to either:
A. Make her lose her guard and deliver the fry in an unprotected area of the tank so that they can eat them as she gives birth to them, or
B. So she dies and they can munch on her dead body.
Not all fish do this but there are some fish with a bigger tendancy to do so than others; if you have a pregnant guppy in the tank with tiger barbs for example, the tiger barbs will almost certainly harrass the mother and eat as many fry as they can.
Not only will you be likely to lose alot of fry from this but also the pregnant fish could die from stress, so in this case I think it advised she is separated from the tiger barbs before she delivers the fry.
On the other hand it is only advised you put guppy or platy sized fish in breeding nets and only one per net, if the fish is bigger than a guppy/platy the stress from the net usually outweighs giving birth in the main tank.
You should aim to only have her in the net for a maximum of 4 days, after that release her back into the main tank.
Setting up the breeding net; when you set up the net, try to put it where it isn't directly under the tank lights (if you can't find anywhere, find somwhere to shade it) but still has a good flow/current from the filter.
Put a piece of plant in the net and rock to help weigh the net down (the plant will help make the pregnant fish feel less stressed and more at home).
Somtimes a livebearer can experience alot of difficulty during the fry birthing process and can die from the stress or fry stuck in her.
Here's what you can do to help try and save the fry in these situations;
A. The pregnant fish is having alot of birthing difficulties and is desperatly trying to expell a fry for hours (you will know because her tail will have become bent to one side and she will be hanging around a spot in the bottom of the tank) and you are positive she is going to die very soon.
I have heard what various people do in this situation is catch the pregnant female and very gently give her belly a very light sqeeze in order to help her expell it; apparently this can work.
B. The pregnant fish has suddenly died while trying to give birth; make sure you have somthing sharp like a razor blade at hand and cut her belly open and remove the fry and put them into water.
This can only be attempted with any success straight after she has died as the fry will die within minutes her death.
Survival rates vary alot from this and i wouldn't expect anymore than a 50% survival rate from this but it is still worth it I believe.
This is what I do when it comes to raising livebearer fry (ps: it is possible to feed them crushed fish flakes throughout their fryhood but this often leads to lower fry survival rates and poorer quality fry/feeding complications);
A. For the first 2 weeks I feed them Liquifry no.1 as this fry food is easy to eat for them and has nutrition in it suitable for this early stage of life- you can continue on this for a month if you like but some people report fry losses from feeding this in the long run as the frys' diet changes.
B. After the liquifry, i then move them onto TetraMinfry or "first bites" by Hikari as these powdered fry foods are very nutritious and although they can be fed throughrout the entire fish's life, they become unsuitable due to their powdered form and the frys literally growing mouth afte 4 months of age.
At 4 months I move them onto fish flakes of suitable size.
C. During the 6 month main growing stage of the frys' life, it is good to also feed them alternative foods like crushed freeze-dried tubifex/daphinia/bloodworm once every 4 days as these foods offer extra protein for the rapidly growing fry.
Most livebearers like platys and guppys take about 6 months to mature although mollies and swordtails can take up to a year+.
Sexing the fry;
In the early stages it is near impossible to tell the frys' sexes apart for the first 3 months. From my observations though I noticed particually in guppy fry, the male fry grow faster than the females and are the first to get extra colors on them in places like their tails that they will have much more of in later life i.e colors like reds; metallic colors are the last to develop.
At around 5 months of age when the fry are showing clear signs of their sexuality, some appear to turn from female to male - that is because all fry appear female when very young and it is the males sexual organs the are some of the last things to develop and somtimes you can have late developers.
The fry will be able to breed themselves at 6 months of age but rarely any earlier than this.
You should start separating the genders as soon as the males begin to appear to prevent unecessary inbreeding and fighting/harrassment towards each other.
A picture of a female giving birth (thanks to bloozoo2)
Edit: One more thing we wanted to add:
So you've heard about the inch per gallon rule. That's an okay rule to follow, but there are some exceptions. For example, In a 10 gallon it is advised you don't keep anymore than 5 Guppies max. But for Mollies, for example, it is advised you don't put anymore than 6 in a 20 gallon because they need more space than Guppies despite the inch per gallon rule claiming there's another 2 inchs of fish space left (Mollies grow to 3-4 inchs)- you can only put 2 Mollies in a 10 gallon and this is for a short period of time. They will grow way too big for that tank, come old enough. The only fish really reccommended for a 10 gallon long term are Guppies and Platies.
Just wanted to give a very special THANKS! to Toxis-Phoenix, for helping me out with this article!