5 Molly Fish Giving Birth Signs

5 Molly Fish Giving Birth Signs7 mins read

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Tal Halperin
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If you want to breed Molly fish, you may be wondering what are the main molly fish giving birth signs and symptoms.

Fish have a lot of behaviors that humans may not recognize at first. Generally, it helps to understand them so you can spot if anything is going wrong.

That said, the molly fish pregnancy cycle is very simple. These are one of the easiest species of freshwater aquarium fish to breed, and that’s for a good reason.

These livebearing fish are in the family Poecilidae with other livebearers such as guppies, platies, and swordtails. And, they mate so readily that many fishkeepers recommend balancing the sex ratio with a surplus of females. This is so you don’t end up with unwanted mating!

Therefore, you may end up with fish pregnancy on your hands – wanted or unwanted. Either way, it’s important to know what to look out for. This includes knowing the signs of a pregnant molly fish, plus when your fish is about to give birth. Read on to find out what to look for.

Top 5 Molly Fish Giving Birth Signs

Top 5 molly fish giving birth signs
Molly Fish may display other behavioral changes before giving birth such as acting more defensive towards other fish or avoiding them.

1. Hiding

Your Molly Fish hiding is a sign of pregnancy that can easily worry beginner fishkeepers.

The question ‘is your molly fish pregnant’ is often preferable to many diseases, too. However, in the later stages of pregnancy you will notice your Molly Fish hiding with a different intent.

In the wild, Mollies and their fry are small enough to be potential food. This includes a wide variety of predators, including larger fish, birds, and frogs. Therefore, your molly fish isn’t just shy!

Instead, your Molly is looking for a safe place to give birth. This is because during the labor process she will be unable to swim away from any danger.

Thus, a pregnant molly fish will most likely choose somewhere that is sheltered to give birth. If you have a corner of the tank with lots of plants, do not be surprised if your Molly Fish makes a beeline for this.

Molly Fish will hang around near the bottom of the tank near the gravel as the fry emerge, as here they spend less effort staying afloat.

Other Behavioral Changes

Apart from hiding, Molly Fish may display other behavioral changes before giving birth such as acting more defensive toward other fish or avoiding them. As the growing fry require more oxygen, you may also see female Mollies breathing from the surface more frequently in the late stages of pregnancy.  In addition, if you have a heater, some fishkeepers report that Mollies will hang around near this heater as the warm temperatures facilitate the birthing process.

Appetite Loss:

Right before giving birth, despite her increased appetite throughout the rest of the gestation period, the female Molly will lower her appetite, as feeding will interfere with the delivery of the fry.

2. Dark Gravid Spot

Can Molly Fish fight?
The dark color of the gravid spot is another surefire indicator that your Molly Fish is near giving birth.

The dark color of the gravid spot is another surefire indicator that your Molly Fish is near giving birth. In the very latest stages of Molly Fish pregnancy, this gravid spot will appear almost black.

However, in a black Molly Fish, remember you won’t be able to see this sign.

Other Physical Changes

Dark spots may form on your Molly Fish near the anal vent during later stages of pregnancy. These generally only appear near the moment of giving birth.

However, your Molly Fish will also display physical symptoms in the lead-up to the actual labor process. This can include miniature contractions, with the tail quivering or body shaking.

3. Distended Stomach

When Molly Fish are in the later stages of pregnancy they have very distended stomachs.

These can be completely convex (rounded, and protruding outwards) from your fish’s body. It can look as if your Molly Fish is carrying up to the same weight as her own body! Indeed, in these later stages of pregnancy, your fish will find it a little more difficult to move and swim around.

Visibility Of Fry

Depending on the color of your pregnant molly fish, you may be able to see the developing fry inside the uterus of the mother. Most easily visible are their eyes, which tend to look like little black dots. This is easiest if you have a light-colored Molly like the Dalmatian Molly.

For the most part, Molly Fish fry is transparent or translucent when they are first born, only darkening to their original color when they grow older.

4. Contractions

You will know that your Molly Fish is finally giving birth once you start noticing contractions. These generally look like spasms that happen throughout the whole of your fish’s body.

Your fish will swim to the bottom of the tank and hover just above the substrate. You will see shivers that pass through your fish’s body and push the fry out of the uterus. Fry can take anything from around 2-10 seconds to emerge from the mother’s body.

Author’s Note: Complications arise when fry get stuck, take longer to emerge, or when two fry are born at once. This can put undue pressure on the other and on the fry, leading to premature death of either or both. There’s not much you can do to stop this once it happens but it’s easy to prevent it and make labor easier by raising the tank temperature by a degree or so – the warmth helps facilitate contractions.

5. Emergence Of The Fry

Emergence Of The molly Fry
Once the fry have emerged, they generally start swimming within a few seconds of entering the water. Image from Flickr

The actual birth process of Molly Fish can be more intense compared to egg-laying fish. As livebearers, the proportionate size of molly fish fry is comparatively large.

Along with the fry, you may see other things emerge from the mother molly’s uterus during the birthing process. The most noticeable of these is the yolk sac of the eggs. This gives the baby fish something to feed on and provides extra nutrients. This tends to be a yellowish color and will quickly dissipate in the water as the fry pass out your mother fish’s body.

Once the fry emerge, they generally start swimming within a few seconds of entering the water. It may take as long as 24 hours for the mother Molly to give birth to all of the fish fry. During this time, she can become very exhausted.

Once fewer fry emerge from her body, contractions likewise become less intense. At this stage, it is best to wait a few minutes. Then, feed her some high-protein food so she can regain her energy.

Author’s Note: Don’t worry! If you’ve made it this far, and your mother fish is still healthy and most of the fry have been delivered alive, then congratulations – although mollies are easy to breed, this is a sign your tank conditions are great and your fish feel safe and are physically strong and healthy.

So, these are the 5 main molly fish giving birth signs. However, if you are earlier in the molly fish pregnancy cycle, and wondering ‘is my molly fish pregnant’, here are some easy ways to tell:

Is My Molly Fish Pregnant?

In the early stages of Molly Fish pregnancy, you may confuse the symptoms with other conditions for fish. In fact, pregnancy can mimic digestive issues, bloating, or even a serious disease called dropsy. However, in the later stages of Molly Fish pregnancy, it becomes unmistakable that your female molly is carrying fry.

How To Spot A Pregnant Molly Fish

What fish cannot live with Mollies?
A pregnant Molly Fish is very visible with a heavily distended abdomen that curves out from underneath the fish’s body in a C shape.

A pregnant molly fish is very visible.  Normally, she will have a heavily distended abdomen that curves out from underneath the fish’s body in a C shape.

However, beyond this, there are also other signs of pregnancy you can spot. These include the following:

1. Gravid Spot

The gravid spot is a dark spot near the tail of your fish that starts off as a pale color. Then, it gradually darkens to black further into the gestation period. In it, you will be able to see the growing fish fry inside the mother’s body.

However, the gravid spot is not the only appearance change. In addition to this and your molly’s rounded stomach, in the later stages of pregnancy, you may even be able to see through your fish’s body. At this time, you can even look into the uterus where the eyes of the fish fry are visible as small black dots.

Author’s Note:  Small white dots can sometimes appear around the gravid spot when your molly is approaching the time of giving birth. These indicate that baby fish will follow not long after!

2. Behavioral Changes

Behavioral changes in pregnancy Molly Fish are possible to mistake for disease, but when you are familiar with molly behavior, you will notice that there are significant differences. One of the main changes is that your fish may hide or seem relatively lethargic. Fish may become shyer and less curious, exploring the tank less frequently than they did before.

In these circumstances, you may fear that your fish is sick. However, so long as she is eating, it is more likely these changes point to pregnancy as opposed to disease. Remember that when carrying eggs your molly’s natural instincts hardwire her to want to defend them.

At all costs, she will try to keep herself safe so that no harm comes to the growing young. As a result, she may be less feisty than usual.

However, if she does not show other signs of disease like difficulty staying afloat, sore or ragged fins, or difficulty swimming, it’s safe to say that you may soon have baby fish in your tank.

Author’s Note: Increased appetite really is an important change during female Molly Fish pregnancy. In fact, this is because your fish is eating not only the amount normally needed for her to swim and stay alive, but also enough to create the growing fish fry in her uterus. Therefore, you may find she needs more protein, and indeed, feeding more protein and feeding little and often can help ensure your fish is strong enough that there are no complications during the pregnancy.

3. The Mating Process

Last but not least, if you have spotted your Molly Fish mating, you can strongly predict pregnancy will follow. if this happens and your female molly then shows some of the above symptoms, your fish is likely pregnant.

However, what does mating look like within the molly fish pregnancy cycle?

Molly fish mating happens quickly. Therefore, you can mistake it for run-of-the-mill tank disputes or chasing behavior. It can also be affected by the presence of competing fish, so a good environment is best to facilitate mating.

In the mating process, the male fish insets a specialized anal fin called a gonopodium into the female’s vent. There, he fertilizes the eggs that she is carrying in her body. This is the part that happens very quickly and that you may miss. On the other hand, the courtship that leads up to it is easy to notice if you know what to look for.

Author’s Note: Once fertilized, the eggs inside your female Molly fish’s body will grow into young fish (fry) and when she is ready to give birth she will push them out of her body where they are then immediately able to start swimming.

Molly Fish Pregnancy Cycle

Overall, the Molly Fish pregnancy cycle is relatively short and simple. Starting with the courtship process and ending with the birth of the fry, it’s a great way to learn about breeding fish for beginners.

If you take good care of your fish, you will most likely see all the stages. If you know what you are doing, it is easy to take care of pregnant Molly Fish.

In the end, the entire process takes about 4-6 weeks. This is much longer than many egg-laying fish which lay eggs that hatch within 2-4 days. It may seem like a while, but take good care of your fish and before you know it, they will be giving birth.

Bottom Line

Molly Fish that is pregnant
Overall the idea of your fish giving birth to live young may sound like it requires a lot of care and intervention on your part. However, these are strong, hardy fish (like the Sailfin Molly pictured)

Overall the idea of your fish giving birth to live young may sound like it requires a lot of care and intervention on your part. However, like many natural processes in the aquarium, it is actually very hands-off and does not require much input from you.

Therefore, even if you are a beginner who has never bred your fish before if you do end up with a pregnant Molly Fish, it’s most likely everything will go off without a hitch.

Frequently Asked Questions

Do Molly Fish die after giving birth?
As a rule, if you look after them well, Molly fish should not die after giving birth. Except for species such as the cardinal tetra, which are annual species and die after spawning in the wild, breeding is a natural part of your pet’s lifecycle and shouldn’t carry a death sentence. If your Molly fish dies after or during giving birth this can be due to complications in the delivery process such as if the water is not warm enough to facilitate contractions, as well as due to other conditions that can affect your fish’s stamina such as water quality in the tank. However, if you keep your fish happy and healthy, there is no reason for her to die during labor.
How many fry can Molly Fish give birth to at once?
A Molly Fish can give birth to up to 40 to 60 baby fish (fry) at once, sometimes even up to eighty in cases such as that of the Dalmatian molly. Molly Fish give birth to this many fry because in the wild they are prey. Therefore it is beneficial for them to have a lot of offspring in case some of these offspring are eaten by a larger predator, or alternatively, die during the delivery process.
What to do about an unwanted Molly Fish pregnancy?
If you have a Molly Fish that is pregnant but you don’t want to keep the offspring, the best thing you can do is to let the pregnancy run its natural course and wait until the mother gives birth before humanely disposing of the fry. You can either separate the fry from the mother after they are born and add a natural anesthetic such as clove oil to the water, which will humanely kill the fry, or you may in fact choose to keep and sell them. Depending on the color of your fry, Molly Fish can fetch up to 4 USD. Even though it doesn’t sound like a lot, it can add up, and social media makes it easier than ever to sell baby fish providing you have space to keep them beforehand.
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Sydney Perry

Sydney Perry has loved fish since she was a child and has enjoyed keeping many varieties over the years, ranging from black moors and shubunkins to betta fish. As a lover of nature and of Japanese culture, her dream tank is an Iwagumi aquascape, combining fish with carefully crafted aquatic landscapes in miniature.