Mystery Snail Eggs 101: Care, Stages, Fertilization & More

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Even after years of experience, I acknowledge that raising mystery snail eggs can be challenging. That is especially true for those who are new to this hobby, as these little things raise tons of questions.

Therefore, after a lot of trial and error, I decided to combine the most frequently asked questions into one article. In many cases, I will link to another article I wrote so that you get a better understanding.

In the first part of this article, I will list some essential tips that will help you care for your mystery snail eggs and keep a large portion of them alive.

For those of you who are in a rush, here is a table that gathers some of the most crucial information:

Temperature68-84° F (20-29° C)
Growing duration2-3 weeks
Number of eggs50-500
How many hatch20-40
How often laidWeekly (for 4.5 months)
Distance from water3-4 inches
Can be underwater?No
About to hatch mystery snail eggs vs. dried unfertilized eggs.

What Should I Know Before Hatching Mystery Snail Eggs?

Mystery snails breed quickly and easily. But there are some key things you should know before trying to hatch their eggs:

1. Mystery Snails Need A Proper Breeding Ground

The sticky substance that holds the eggs together will also bind the clutch to a hard surface. A study published in 2018 (Siti Norasikin Ismail, Mashhor Mansor, and Nurul Izzati) wanted to understand the behavior of golden apple snails.[1]

It found that the creatures were more likely (43 percent) to lay their eggs on the stems and leaves of plants even though they had more rigid surfaces, such as rocks and boats, in the vicinity.

The study looked at golden apple snails in the wild. As such, you can’t expect mystery snails in an aquarium to behave in a similar manner.

They are more likely to attach their eggs to the tank walls, especially in the absence of alternative surfaces.

That being said, you can aid the breeding process by adding aquatic plants that can accommodate the eggs.

2. There Should Be Space From The Water

Mystery snail eggs cannot hatch underwater. This is why the mothers lay their eggs above the waterline. This is also the reason why aquarists are encouraged to leave several inches of space above the waterline.

You can fill the tank to the top if you want, but the practice is not ideal. First of all, the aquarium will make a mess because the water is more likely to splash on the floor.

Secondly, fish species like bettas will use the opportunity to jump out of the tank unless you add a lid.

If you have mystery snails, all their embryos will drown because the creatures cannot hatch under water. Lower the waterline by three or four inches.

3. Some Eggs Are Usually Not Be Fertilized

You can’t hatch infertile eggs. But how can you identify fertile eggs? Your best option is to observe the clutch. Fertile and infertile eggs are virtually identical at the start. They are soft, delicate, and pink.

However, fertilized eggs will change over the next few days and weeks, turning from pink to a darker color that reflects the hardening shell surrounding the embryos.

The eggs will also grow in size. To be more specific, they will look fuller than usual before taking on an irregular shape. If you look closely enough, you will notice black spots in the eggs.[2]

These black spots are the baby snails developing within. Some clutches will manifest a white color that occasionally signifies the presence of mold.

However, mold shouldn’t scare you. It shows that a cluster is on the verge of hatching. Eventually, the babies will eat their way out of the sack.

Fertilized eggs are unpleasant to look at, especially when they develop a slimy texture. In fact, an amateur may dismiss them as unfertilized or rotten.

On the other hand, unfertilized eggs don’t seem so bad. They typically maintain their pink color. That color will persist over the days and weeks.

You won’t notice any black spots, dark colors, or mold. Instead, the eggs will develop a nasty odor, proving once and for all that a male snail did not fertilize them.

A clutch of mystery snail eggs on the aquarium’s wall.

4. The Eggs Shouldn’t Be Moved Right Away

If you’ve decided to move the eggs from their hard surface in the main tank, wait 48 hours. The clutch is too soft at the start.

By trying to move the eggs, you run the risk of damaging them. But if you wait 48 hours, the eggs will harden to the point where you can safely move them.[3]

5. Many Aquarists Throw A Few Batches

People understand the importance of throwing unfertilized eggs away before they compromise the water’s chemistry. But they don’t seem to realize they can do the same for fertilized eggs.

Mystery snails can lay hundreds of eggs per year. Unless you run a mystery snail store, you can’t keep all the eggs a female snail produces. The creatures will quickly overwhelm your tank.

Even experienced aquarists will throw the majority of the eggs away, keeping only a few clutches. But your decision will depend on the size and number of aquariums in your home.

If you can afford to raise every baby that hatches from the cluster, feel free to do so. But if you decide to dispose of the eggs, fight the urge to flush them down the toilet.

This study from the Philippine Rice Research Institute, looking at the management of invasive apple snails, has highlighted the destructive impact invasive snail species can have on agriculture and native ecosystems.[4]

If you have unwanted eggs, place the clutches in a plastic bag before freezing and crushing them.

6. The Eggs Won’t Hatch Without A Male

You require both genders to produce viable eggs. The female can lay eggs without a male, but you can’t expect them to hatch. After all, they are not fertilized.

The mother will search for a suitable breeding ground to lay her eggs in the afternoon, evening, or night.

The clutch looks like a dense bunch of grapes. The eggs have a sticky substance that holds them together.

How Do I Hatch Mystery Snail Eggs?

If you have a decent collection of fertile mystery snail eggs that you’re willing to raise and you’re trying to identify a suitable means of hatching them, your options will include the following:

1. Leave Them Alone

This sounds counterintuitive because snail eggs are so small and delicate. But mystery snail eggs don’t need your help.

If they have sufficient space above the waterline and moist conditions, they will hatch after a few weeks without your direct involvement.[5]

Your assistance only matters when the humidity drops dramatically. These creatures require warm and moist conditions. Therefore, you should maintain a healthy distance between a clutch of eggs and artificial lighting.

Admittedly, you don’t control the position of the eggs. The snail will lay the cluster wherever it chooses.

Your only course of action is to remove the clutch from the tank if its proximity to the light is causing the eggs to dry out.

Although, you can also spray the eggs with water to keep them moist. Once you detach a clutch from a hard surface, you can’t re-attach it.

Keep a close eye on the eggs in a community tank. This study (edited by Manabu Sakakibara) found that egg hatching success reduces in the presence of predators.[6]

If the tank has aggressive fish species with a penchant for eating mystery snail eggs, move the clutch to a separate container.

You can take a similar step if the clutch falls into the water. Eggs that fall in the water are not a lost cause. Yes, the embryos can drown, but only if you allow the clutch to linger underwater.

If you remove the eggs and store them on a damp towel in a container, they will hatch. You don’t have to clean or dry them beforehand.

2. Use A Breeding Trap

If you’ve ever raised brooding fish, you probably have one or two breeding traps on hand. Install the trap above the waterline and place Styrofoam on the water. You can raise the Styrofoam with elastics where necessary.

Then, cover the trap, but don’t forget to look for signs of drying. Some aquarists use a finger to moisten the clutch.

Others are hesitant to handle the eggs with their bare hands because they are well aware of the diseases that snails carry.

This study from the Pan American Health Organization explores the role snails play as intermediate hosts for schistosomiasis. Snails encounter Schistosoma mansoni in fecal matter.[7]

But stories of aquarists contracting diseases from mystery snail eggs are rare. Although, that shouldn’t stop you from applying caution.

3. Use A Separate Container


  • Get a container with a lid and fill half of it with water.
  • Get a piece of Styrofoam and float it on the water.
  • Place the eggs on the Styrofoam to keep them moist.
  • Close the container with a lid.

Some people will put holes in the cover to allow fresh air to enter the container. But others have hatched mystery snail eggs without these holes.

However, they will open the container once a day to allow fresh air to enter. The location of the container matters. Technically speaking, any warm spot will do.

For instance, you can place the box behind a refrigerator. Although, you are probably better off floating the container in the aquarium.

That is because the main tank typically features the right temperature for the eggs. Otherwise, the eggs wouldn’t have been laid.

4. Use A Plastic Bag

It is common practice to place egg clutches on a damp paper towel inside a container. Most aquarists rarely use Styrofoam.

Damp paper towels are more convenient because you don’t have to float them in water. However, some people prefer plastic bags.

You have to wrap the clutch in a damp paper towel. Then, place it in the plastic bag before finding a warm location to store it.

Regardless of the method you choose, observe the eggs. Some people place their eggs in separate containers and forget about them for the next two to three weeks.

They don’t realize that some eggs can go bad and rot. Others will dry out because the temperature rose suddenly while the humidity dropped.

Mystery snail eggs are sturdy. You can save them if you take swift action. But you can only take swift action if you keep an eye on the clutch. Otherwise, the eggs will dry out before you can even notice.

How Long Do Mystery Snail Eggs Take To Hatch?

It takes approximately two to three weeks for mystery snail eggs to hatch. During that time, the eggs must remain 3-4 inches above the waterline at a temperature ranging from 68 to 84 degrees F.

You need patience with mystery snail eggs; there is no doubt about it. Don’t expect to see changes immediately. Even if the eggs are fertilized, it takes time for the embryos to grow.

Many fish owners actually see this as an advantage since you have plenty of time to prepare for the baby snails. You also have a window to think about where to raise the eggs.

Sounds interesting? Feel free to check this article, where I discussed how long mystery snail eggs take to hatch. I also mentioned why the eggs don’t hatch or change their appearance.

How Many Eggs Does A Mystery Snail Lay?

Mystery snails can lay up to 500 eggs in a single clutch, of which 20 to 40 will eventually hatch. The spawning season typically lasts for 4 to 5 months. During that time, mystery snails can lay eggs every week.

Aquarists usually panic when they hear that mystery snails can lay so many eggs. But even if the mother lays hundreds of eggs, only a small fraction will hatch.

Some eggs won’t be fertilized, while others will die during the growth phase. Either way, you won’t have hundreds of babies after a single batch. But indeed, even a few dozen is plenty for some fish owners.

Still curious? Feel free to check this article, where I discussed how many eggs mystery snails lay. I also answered questions like how often mystery snails lay eggs and whether they are likely to overpopulate your tank.

How To Tell If Mystery Snail Eggs Are Fertilized?

Fertilized mystery snail eggs darken towards the end of the first week and become irregular in shape. Their shells will also harden, and at a certain point, they will look like they have developed mold.

If your mystery snail eggs develop the signs above, they are probably fertilized and will hatch within the following week.

Some owners get nervous when the eggs start looking like mold. But that is perfectly normal. It is merely the baby snails growing inside.

On the other hand, unfertilized eggs will remain pinkish, round, and small. If more than a week has passed and the eggs haven’t changed, they are probably not fertilized.

Remember that a single clutch may contain fertilized and unfertilized eggs. That is usually the case, as the snails don’t fertilize hundreds of eggs in a single session.

Caught your attention? Here is an article where I explained how to tell if mystery snail eggs are fertilized. You will find some detailed pictures for a better visual understanding.

What Are The Mystery Snail Eggs Growth Stages?

There are four main growth stages for mystery snail eggs:

  • Stage 1 (days 1-2): Pinkish, round, soft, and small. 
  • Stage 2 (days 3-7): Garnet brown, hardening shell. 
  • Stage 3 (days 7-10): Gray shades, irregular shapes. 
  • Stage 4 (days 11-21): Moldy appearance, varying sizes.

During stage one, the fertilized eggs will appear like their unfertilized counterparts. But that doesn’t last long.

After 48 hours, the fertilized eggs will develop garnet brown shades. Also, if you touch them gently, you’ll notice that their shells become harder.

If you wish to grow the eggs in an incubator, you can transfer them at stage two. You may break a few, but most of them should remain intact.

Wish to learn more? Feel free to check the following article, where I discussed the mystery snail egg growth stages. I also embedded an outstanding video that follows the development of the eggs (from start to finish).

Do Mystery Snail Eggs Need To Be In Water?

Mystery snail eggs shouldn’t be in the water, or the baby snails will suffocate. Even though grown-up snails have gills and lungs, the eggs won’t survive if kept underwater for more than 24 hours.

It is natural to think that mystery snail eggs should be underwater. That is because adult mystery snails stay underwater almost all day long.

Yet, every once in a while, mystery snails climb to the top to extract oxygen from the surface. They cannot remain underwater forever.

That is why the female mystery snail lays her eggs above the waterline. She knows that the eggs will drown otherwise.

Sounds interesting? Check out this article where I answered whether mystery snails need to be in the water. You will also find the precise steps to take if the eggs accidentally fall into the water.

Can You Leave Mystery Snail Eggs In Your Tank?

You can leave your mystery snail eggs in the original tank. However, you risk them falling into the water or getting eaten by fish. A better practice would be moving them to an incubator after two days.

As a rule of thumb, if the environment is comfortable enough for the snail to lay its eggs, it is suitable for the eggs to grow and eventually hatch.

Otherwise, your mystery snail wouldn’t have laid the eggs in the first place. But that isn’t an ideal location, as the eggs can be easily detached and fall.

As mentioned earlier, after 48 hours, the shell becomes harder (assuming that the eggs are fertilized). That would be the right time to move them to an incubator.

Still curious? Check out this article, where I discussed whether you could leave mystery snail eggs in your tank. In there, I take you step-by-step through the process of growing the eggs outside your tank.

Do Mystery Snails Take Care Of Their Eggs?

Mystery snails don’t actively grow their eggs. They are self-sustaining and hatch on their own. Fortunately, unlike other snail species, mystery snails are also less likely to eat their eggs.

Mystery snails are different from egg-laying fish that consistently protect and cultivate their eggs. Once the eggs are laid, there is a little chance you’ll see an adult snail visiting them.

Caught your attention? Check out this article, where I discussed whether mystery snails take care of their eggs. I also mentioned a few tips to help you protect the eggs yourself.

What To Do If My Mystery Snail Lays Eggs?

You can do three main things with mystery snail eggs:

  • Raise them in a moist and warm environment. 
  • Eliminate the eggs manually. 
  • Use them as a food source for your fish.

Many aquarists go with option number three. That is because they don’t want a new population of mystery snails, and since the eggs are highly nutritious.

But you can also raise the eggs, as I discussed in the first part of this article. Either way, you have two to three weeks to decide.

Wish to learn more? Here is an article where I presented what you could do with mystery snail eggs. There, you will find a detailed explanation regarding each option.

Will Fish Eat Mystery Snail Eggs?

Yes, aquarium fish will eat mystery snail eggs. Being opportunistic feeders, aquarium fish will eat whatever fits in their mouths. Some aquarists even raise those eggs for the single purpose of feeding their fish.

If you found a clutch of mystery snail eggs and wish to get rid of them, feeding them to your fish is an excellent solution.

Just make sure no egg is left behind. If a few get buried inside your substrate, they will rot and contaminate your tank with ammonia.

Sounds interesting? Here you will find all the information on whether fish eat mystery snail eggs. I also showed the right way to feed the eggs to your fish.

How To Get Rid Of Mystery Snail Eggs

There are a few ways to get rid of mystery snail eggs. You can:

  • Use the eggs as a food source for your fish.
  • Scrape them off by using a credit card.
  • Cover the eggs with water.
  • Remove the lid, so the eggs dry out.

Each way will ensure that the eggs eventually die. If you scrape them off the aquarium glass, place them in a bag and put them in the freezer.

After the eggs freeze, you can crush the clutch and throw the remains in a bin. Yet, I personally prefer feeding them to aquarium fish.

Still curious? Here you will find my complete guide on how to get rid of mystery snail eggs. I also included an excellent video showing how to remove eggs buried in the aquarium soil.