One exciting part of keeping mystery snails is watching a female lay eggs. Those pink clusters above the waterline spark curiosity—and often the question: are these eggs fertile? The good news is that you can tell if mystery snail eggs are fertile only with patience and careful observation.
First, let’s understand mystery snail reproduction. Mystery snails are not hermaphrodites. They have separate males and females. A female needs to mate with a male to produce fertile eggs. She can store sperm for months, even up to a year in some cases. This means she might lay fertile clutches long after the male is gone from the tank.
Females lay eggs out of water to protect them from fish and poor conditions below the surface. The clutch forms a firm, pink or creamy mass on glass, decorations, or the tank lid. A single clutch can hold dozens to hundreds of eggs, depending on the female’s size and health.
Right after laying, all clutches look similar—bright pink to pale cream, soft but sticky, and rounded. You cannot tell fertility on day one. It takes time for development to show.
Check here what to do if mystery snail eggs fell in water
How to tell if Mystery Snail Eggs are Fertile
A mystery snail can lay up to 300 eggs, but for them to hatch, they must be fertilized. However, a mystery snail can still lay unfertilized eggs if it does not mate with a male. If you intend to increase the flock of your mystery snail, then you must keep both genders.
When mystery snail eggs are laid, they have a pink color and smooth consistency, and it is hard to know if they are fertilized or not. However, after about two weeks, you can tell the difference.
1. Fertile Eggs will Grow and Change Color
In the first 48 hours after the eggs are laid, they are small, pink in color, and soft. Afterward, they will start to harden and change their color to brown. They will also grow in size and have dark spots when they approach hatching. The dark spots are baby mystery snails.
The eggshell will also start to thin as the baby mystery snails will eat the inner of the shell as they try to come out. They will appear dark grey with an irregular shape. Infertile eggs will have a uniform size and color. They will stay pale, pink, or transparent.
2. Having a Male Mystery Snail
As earlier stated, mystery snails are not asexual, and for breeding to occur, a male and a female are required. When a female mystery snail is ready for breeding, she will turn translucent.
The male mystery snail will mount on her and fertilize her eggs. You will notice because it will take more than a few hours.
If you only have a female mystery snail, then her eggs will obviously be unfertilized. However, if you recently bought her, they may be fertilized because a female mystery snail can hold fertile sperm for up to 140 days.
3. The Paper Towel Test
This simple trick helps confirm fertility, especially if you move the clutch. Gently remove the clutch after it hardens (wait 1-2 days post-laying). Place it on a damp paper towel in a covered container (like a plastic box with air holes). Keep the towel moist but not soaking.
Infertile eggs often leak a red or pink stain onto the towel. Fertile ones do not stain—they stay clean.
This test works because infertile eggs contain yolk or fluid that bleeds out.
4. Smell the Eggs
Fertile eggs have little to no odor. A faint earthy smell is okay. Infertile ones develop a rotten or funky smell as they decay. If it stinks after a week, they are likely not viable.
5. Dark Spots or Movement
Hold the clutch of eggs up to the light or use a flashlight. In fertile eggs, you might spot tiny dark centers (embryos) after 1-2 weeks. Later stages show faint movement in some eggs.
Infertile eggs look uniform—no dots, no shadows.
What to do with Fertile Mystery Snail Eggs
When you let your mystery snail eggs hatch, you must be prepared to rear many baby snails. You will be required to provide another tank and food for the babies. Afterward, you can decide to keep them, give them away or sell them. You can either choose to let them hatch on their own or put them in an incubator.
Fertile mystery snail eggs will hatch in about two to three weeks. For this to happen, the following conditions will be required:
- High air humidity
- The temperature of between 76 and 82 degrees Fahrenheit.
- They should stay above the water surface.
Fertile mystery snail eggs will still hatch even when left in the tank. However, their hatching success rate is low because they risk falling into the tank. The mystery snail babies will emerge and drop directly into the water. When using this method, ensure to move any tank mate that could eat the hatchlings.
Set up an Incubator
Incubating the eggs is another way of increasing the hatching success rate. When moving the eggs to the incubator, you must be very careful not to crush them. You should wait for at least two days for them to harden before moving them.
Follow the following steps while moving them to the incubator
- Prepare the incubation box. You can also use a container with a secure lid.
- Deep three paper towels in water, squeeze the water out and place them at the bottom of the incubation box.
- Carefully move the eggs and put them on the damp paper towel.
- Seal the incubation box and place it in a warm and humid place. Floating the box in the tank is also okay.
What to do with Infertile Mystery Snail Eggs
If the eggs are not hatching, it means they are infertile. Leaving them in the tank can become a hazard because harmful bacteria can breed in them and affect other tank mates. Therefore, it is essential to remove and dispose of them properly.
1. Crush the Eggs
Put the infertile eggs in a polythene bag, crush them, and dispose of them in the dustbin. Crushing them ensures that if there are any fertile eggs, they do not hatch in the wild.
Freeze the Eggs
You can also wrap the infertile eggs with a paper towel and put them in the freezer for about twenty-four hours. Afterward, you can discard them in the dustbin or flush them in the toilet.
Conclusion
Differentiating between fertile and infertile mystery snail eggs will be hard in the first week after being laid. Therefore, you can wait for at least two weeks to be sure. Infertile eggs will smell bad, stain if placed on a paper towel, and will not change in size. Fertile eggs will grow in size and will have dark spots when approaching their hatching day.
It is crucial to dispose of infertile eggs because harmful bacteria can breed in them and affect the other tank mates.
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