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Bernie Bernie is offline
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Default Livebearers, Pregnancy & Fry!

This is something I put together from things I have remembered or read over the years and from my own experience when I have kept guppies and platys. Please do not take it as gospel, but it might give those of you keeping Livebearers some hints/guidelines that may be useful.

Please note: The following is in two parts because it is too long to fit into one post.

What to look for in a healthy fish:

Before buying your Livebearer (or any fish) you should try and inspect it closely for any signs of illness. These are just some of the obvious things to look out for!

Fish to buy:

Fish….that have a round/plump abdomen that curves outwards, shows that they have been eating well. The female usually looks fatter than the male. The female will appear even rounder if holding fry.

That breathes slowly and regularly, but sometimes fish may be breathing a bit heavily in the shop tanks because they are overstocked).

That have a healthy looking reddish colour under the gill flaps.

That are holding their fins erect most of the time, with the fins having a well defined shape/edge to them and free from tears (Torn fins can occur periodically from getting caught/cut on décor etc. and will usually heal naturally).

Whose eyes look healthy and clear.

Whose scales are sitting flat. The skin/scales and mouth should be free of any white spots, mold, fungus, or white film.

Fish to avoid:

Fish….that have a concave or sunken looking stomach, could mean that is having trouble eating or the stomach hasn’t formed properly.

That look overly bloated, this could also be a sign of illness.

That is heavily pregnant, where her stomach has a box shape to it and has a large gravid spot. Stress from moving could cause her to abort the fry or even kill her.

That have a deformed body, which is often a sign the fish has been malnourished or lacked essential vitamins and could also be a sign of too much crossbreeding, that fish will probably have a shorter lifespan.

That look like they may be missing a gill cover, this could be due to a deformity at birth or it could have been torn off accidently, this will usually not harm the fish and may even grow back (if torn in a fight) but it could possibly lead to infection at some point.

That have frayed/shredded fins, these are often signs of a disease, although there may be other causes such as fighting etc.

That have clamped fins and shimmies (staying in one spot and moving from side to side) continuously is a definite sign of stress, and that fish will often end up getting a disease and should not be bought.

That has cloudy eyes, or abnormally protruding eyes. This could be a sign of Pop-eye.

That have scales sticking out (pine cone effect) or skin and mouth have white spots, mold, fungus, or white film on it. Sure sign that the fish is definitely ill.

That is staying on its own near the bottom of the tank continuously, it is often a sign that the fish is stressed, exhausted or sick and it is best not to buy that fish.

NOTE: Of course it can be hard to resist buying a sick fish, as most of us want to save them if we can and give them a good home, this is commendable, but sometimes this can be the wrong thing to do, particularly if those fish are going to join our other fish…It can often bring illness into the tank. Although if our fish are very healthy they may not catch an illness, but it is always better to be on the safe side and quarantine new fish for 2 weeks before introducing them to the main tank.

How to sex Livebearers?

Adult male livebearers have a gonopodium which was the anal fin, but it has adapted into the sex organ and has a pointed shape. Males usually are smaller and slimmer. The anal fin on a female is round. (If you go to the gallery section and click on livebearers, you can see the difference between them in some of the pictures).


Most livebearers, although not classed as shoaling fish, do prefer the company of their own species, so it is advisable to always buy at least 2, preferably 3. If keeping both sexes, it is best to always have more females than males and 1 male to 2-3 females is a good ratio, but with swordtails it is better to have 1 male to 4-5 females, because of the aggressive nature the male often has.

You should only buy a single female if she is pregnant, because you will soon have many more. Try to buy fish that are similar in size, as this will help limit any aggression.

Tank size for Livebearers:

My personal opinion is that the minimum size tank for Mollies and Swordtails would be a 15-20 gallon tank, as they tend to grow larger than guppies or platys, and they need more space. They also can be aggressive and giving them more space will help ease any harassment between the sexes. Mollies in particular may need specific water conditions to stay healthy, and researching them first is a good idea. I personally think it is best to keep them in a species specific tank, this enables you to maintain those specific requirements.

Guppies and platys are the ones to go for if you only have a 10 gallon tank, but I wouldn’t put any more than 5 (6 at the most) in there. All livebearers can be big waste producers, so good filtration and water quality is needed.

Last edited by Tim : at .
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Bernie Bernie is offline
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Default Livebearers, Pregnancy & Fry!

(Part 2)

Pregnant behaviour:

There is a 99% chance that if you buy a female livebearer she will be pregnant, even if no males have been around in a while, female livebearers can hold onto the sperm for months, allowing her to produce fry when conditions are favourable, or all males have died. Gestation usually takes approx. 28 days, although it can be from 21 days up to 40 days (I mention this in more detail further on). They can have anywhere between 5-100 fry, but often stays around 10-20. Mollies and Swordtails have been known to take longer, even up to 2-3 months to give birth, possibly because they are a bit larger and may be holding a large number of fry.

Week 1.. of pregnancy, you shouldn’t notice many changes, although if a male is present, he may harass her more than usual and she will become a bit more intolerant of other fish and may seem aggressive towards them.

Week 2.. she may show an increase in appetite, the gravid spot (dark patch below the stomach and near the vent area, said to be the fry developing and their eyes showing through as the females skin becomes more transparent as it stretches with the fry) will start to develop. Although not all livebearers show a gravid spot (please refer to Gravid Spot ? at end of page).

Week 3.. the gravid spot becomes very dark and her stomach may look like it is going to burst and start to get a box shape to it. Her appetite will have increased considerably and she will be much more competitive for food and possibly much more aggressive; you may notice her spending much more time by herself around plants or in a good hiding place, she may also just sit near the bottom of the tank without moving very much. If the female guppy is only holding a few fry, she may drop them at this time.

Week 4 week should see the female begin to drop the fry, although it can take up to 5 weeks, (livebearers can hold onto there fry until they feel conditions are favourable, which can make it difficult to give a specific time frame for dropping of the fry). The birthing or dropping of fry can take between a few hours to a day, sometimes longer, she can just give birth to a few fry at a time and then deliver the rest later on (can be days, or even a week or so later).

During this time it is best to keep her as stress free as possible and moving pregnant females to a breeding tank or net a couple of days before she is expected to give birth is an option particularly if she is in a community tank, sometimes moving her could cause more stress. She can also abort the fry if she experiences a lot of stress or doesn't get enough food. Keeping the tank temp. around 78*, and feeding her a varied/nutritious diet throughout her pregnancy such as bloodworms, brine shrimp, daphnia and high quality flakes etc. and keep water quality conditions high will aid the process.

Note: Livebearers can go through immense stress during birthing and can have problems dropping the fry due to the large number or fry getting stuck. The female can die during/after birth.

Fry tank or Breeding net?

This is often a matter of personal preference. I personally have just left things up to “mother nature” whenever my fish gave birth and in most cases some fry survived being eaten etc. “Survival of the fittest” I guess!

A fry tank is simply a spare tank that is cycled and has adequate heating, filtration and lighting with some plants or floating plants (live/artificial) so they can hide, but not absolutely necessary if they are the only fish in the tank. A good size fry tank is around 10 gallons or bigger if there are going to be hundreds of fry.

You can either place the female in the fry tank a few days before you think she is due to drop the fry or you can leave her in the main tank and then collect the fry and transfer them to the fry tank. If moving them to a fry tank, it should have the same water conditions as the tank they came from so as to help prevent the fry dying from stress/shock and I don’t think it is a good idea to move them too much during the early stages of their development.

Breeding nets are another option, but there is limited space in them if you are putting the expectant female in it or you have more than one pregnant female about to drop fry at the same time. It is also recommended to keep them in a breeding net for no longer than 4 days or so, as being in the net can cause stress. Mollies and swordtails can often be too big to keep in a breeding net.

If using a net, the best position for it is out of direct light, and somewhere it will get adequate water flow. Putting a plant in the net will make her feel more secure and it may also keep the bottom of the net stable. I think the nets are better than the plastic breeding traps because I find that the fry can sometimes fit through the slits and end up in the main tank.

Feeding/Raising your fry:

Fry may not want to eat for 2 days or so after birth, but I think it is best to start feeding them straight, although they will often find minute pieces of food in the gravel or on the plants.

It is best to try and feed fry 3-5 times a day if possible. You can feed them on a number of foods designed for fry such as Liquifry or the powdered fry food, infusoria, baby brine shrimp is very good, crushed up hard boiled egg yolks is another food for fry (a member mentioned in a post, an egg yoke mixture they used, but I can’t find it at the moment). Crushing up normal fish flakes into a very fine powder also works. I have always just used the powdered fry food, b.brine shrimp and crushed flakes.

The fry prefer and will grow faster in warmer temperatures around 77-78* along with regular feeding, nutritious food and clean water conditions. It is safe to put fry back into the main tank when you are sure they are big enough not to get eaten by the other fish. Usually when they are approx. 1 inch is safest, but again it can depend on the type of tank mates it will have. Most livebearers such as platys and guppies take about 6 months to fully mature, although mollies and swordtails may take up to a year.

There will be some fry that may not survive despite everything, due to some of their internal organs (often the lungs or swim bladder) not developing properly.

Sexing fry:

It is virtually impossible to tell the fry’s' sex for the first 3 months. Male fry may grow faster than females and may be the first to start showing a bit of colour which usually shows on the tail fin first. The male’s gonopodium may develop last and start showing around 5 months of age, but some males can be very slow in developing and you may think that a female is turning into a male all of a sudden many months later.

6 months of age is around the time that they can truly start breeding but there may be exceptions to the rule and it is best to separate the sexes as soon as you start noticing the difference, unless you want them to breed, but this is not a good idea as you want to try and avoid any inbreeding.

The Gravid Spot ?:

I will try to clarify this ? as it is often asked about. I believe it basically comes down to this...All livebearers (talking about Guppies, Swordtails, Mollies and Platys’ here) may have a gravid spot to a certain extent. Guppies certainly do and it is particularly pronounced because of their colouring and transparency of their skin. It can show in the other livebearers to varying degrees, but not always...and for the same reason; because it may be hidden by the fish’s natural colouring and their skin isn’t as transparent as that of guppies.

Some livebearers may seem to have a gravid spot constantly, even if they aren’t holding fry and it may just mean that they are mature and have mated at some stage and not necessarily a sign of pregnancy, also some livebearers have a naturally darkened area just above the anal fin. The best sign is that they start getting larger and rounder in the abdomen.

Thanks...The End!!

Footnote: There is a copy of this article in the "Livebearer" forum which is open for any comments/tips/questions etc.

Last edited by Bernie : at .

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