How to Tell if Mystery Snail Eggs Are Fertile

Mystery snails are able to produce and lay infertile clutches of eggs if they haven’t mated. What makes this entire process more complicating is a snail may mate, and then only lay the eggs far into the future. Unlike many other snail species, a mystery snail can not reproduce asexually.

So it’s always a guessing game whether the eggs are fertilized or not. Luckily it’s easy to tell if mystery snail eggs are fertile with just a quick glance.

Fertile Eggs

A fertilized egg with a tiny developing snail in it should have what looks like a little black spot in the middle of the egg. The eggs will look larger and “fuller” with more irregular shaping. The color of the eggs will start to vary as time goes on, showing that they are indeed alive.

You may notice some white developing on some of the eggs. Sometimes this means a fertile egg has died, However, It also means they might be getting ready to hatch. Your eggs may look moldy just before the time comes for the baby snails to break free. This is normal, do not panic.

Protecting Fertile Eggs

If your eggs are fertile, you will need to decide if you want to remove them from your aquarium and place them in their own holding tank, Or on a damp paper towel. Remember to mist them every day.

While it’s not necisary to remove the eggs from the original tank, it comes down to your own unique circumstances. Small snails are vulnerable to many species of fish, bottom feeders and shrimp.

If you think there’s anything in your tank that might threaten the survival of the baby snails, it’s best to remove them to their own tank until they are large enough to no longer be prey.

A good alternative to this would be a breeder box. If you don’t have one you should pick one up. Not only are they very affordable (10$ give or take in most cases), They will make your life considerably easier.

A breeder box will protect the fertile eggs as well as the baby snails until they are big enough to be off the prey list. It also makes a good containment room in case you plan on moving the snails at a later date. Nothing worse than trying to collect 50+ baby snails that blend into the gravel from a tank. Definitely get a breeder box.

Infertile Eggs

Infertile eggs will all look very uniform, and small. There will be no black spots and they will be fairly dark in color. After a week or 2, they will start to put off a unique odor which will be your defacto signal these eggs are infertile.

If you put your eggs on a damp paper towel in order to hatch them outside of the tank, You will notice infertile eggs will stain the wet paper towel with a red substance. Fertile eggs won’t do this!

Another more obvious sign your eggs are infertile is if you don’t even have a male. Sexing Mystery snails go beyond this article, however. A good rule of thumb is if you have more than a handful of snails in a tank, it’s almost a guarantee they are fertile. If you only have a few, then it’s a 50 / 50 shot. Remember, at the beginning of the article we said mystery snails cannot reproduce asexually.

Disposing of Fertile and Infertile Eggs

If for some reason you find yourself needing to dispose of good fertile eggs, Or just to remove some dead infertile eggs, The procedure is the same.

Ye’ old crush and flush.

Yes, it sounds terrible! To us keepers, snails beautiful creatures that deserve life and freedom. They are absolutely stunning in color and life. Unfortunately, the rest of the world doesn’t see it the way we do.

The sad reality is, snails are pests. They destroy crops, vegetation, and ecosystems. That’s why land snails are illegal in the United States and Canada. Those big boys could destroy everything.

Even though mystery snails are much smaller, it is still our responsibility as aquarium snail hobbyists to deal with these eggs in a proper manner, as cruel as it might seem.

Method 1, Crush Them

The first method is the cruelest in our opinion, but also very effective. Simply place the fertile or infertile eggs between some paper towels and start crushing the eggs with your foot or something heavy. Then flush them down the toilet or throw them in the trash.

Why do we take such precautions with infertile eggs? It’s better safe than sorry. Even if an entire clutch seems infertile theirs always a possibility some are not.

Method 2, Freeze the Eggs

This method might be easier for some of you to manage without feeling so terrible. Simply place the eggs in the paper towel like the first method, but place them in the freezer for a few days instead.

Then dispose of them in the same manner, Either by flushing them down the toilet or disposing them into the trash.

The act of freezing will make quick work of the eggs and is considered a more humane method of execution. This is also how we deal with baby mice bred for snake food (I know! D:). Luckily that’s something my family does, not me!

Bottom line

Seeing if a mystery snail egg clutch is alive and well is fairly easy. Just look at the signs in this article. Black spots, irregular shaping, etc.

Remember that it is YOUR DUTY as a qualified and responsible aquarium hobbyist to dispose of any unwanted eggs in a proper manner and to not let them escape into the environment. Even if you think they are dead or infertile!


Owner of and also owner of actual Aquarium Gravel believe it or not! ;). Setting up beautiful aquarium sceneries and habitats since I was very young. Enjoy!

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