Sick Mystery Snails – Possible Causes and Best Treatments

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Mystery snails make an excellent addition to most freshwater tanks!

These colorful snails are helpful to the hobbyist because they graze on detritus, leftover fish food, and some algae species, keeping the tank tidy. In addition, the Mystery snail can make a peaceful companion for feisty fish, such as bettas, and these harmless mollusks are fascinating to watch too.

Unfortunately, just like any other creature in your aquarium, Mystery snails can sometimes get sick.

Read this guide to learn everything you need to know about recognizing health issues with Mystery snails and how to treat them.

What Is a Mystery Snail?

Mystery Snail

Before we look at sickness in these charming little creatures, let’s find out more about Mystery snails.

Mystery snails, Pomacea bridgesii, are medium-sized freshwater aquarium snails that belong to the Ampullariidae family.

Mystery snails are native to South America, inhabiting the lakes, swamps, and rivers of Paraguay, Bolivia, and Brazil. These snails are numerous in the wild environment and are not considered threatened or endangered.

These peaceful, omnivorous snails grow to around 2 inches in diameter, making them ideal for life in a small 5-gallon tank. Mystery snails can live for up to two years when given the proper care and optimum tank conditions.

Colorful Creatures!

Mystery snails come in a wide variety of shell colors and patterns. Sometimes, the snail’s shell is one primary color, or it could be decorated with stripes and bands.

Basic Mystery snail shell colors can be yellow, green, purple, or ivory, and you can also find beautiful variations, including golden, black, blue, reddish-brown, pink, and purple.

Availability of Mystery Snails

Mystery snails are extremely popular in the hobby and are readily available in most pet and fish stores.

You can expect to pay around $6 per snail, although rarer colors can be more expensive. Generally, it’s cheaper to buy a group of six Mystery snails for around $18 to $30, again depending on the colors and markings of the snails offered.

How To Know if Your Mystery Snail Is Healthy

Most Mystery snails are at the most active during the night, resting up during the day. That said, you should still see your snail moving around every now and then.

If your snail slows down and becomes less active, lies on its side, or remains in the same place overnight, then it’s probably a sick snail. In addition, the snail’s shell should be strong and thick. If the shell appears thin or cracked, the creature’s diet is lacking in calcium, and it could die if you don’t fix the problem promptly.

Sickness in Mystery Snails

It’s surprisingly tricky to determine whether your Mystery snail is sick.

For example, these snails can retreat into their shells for days, leading you to believe the creature is sick, although that’s often not the case at all!

How To Recognize a Dying Mystery Snail

Although it sounds crazy, it’s often extremely difficult to tell if your snail is dying or dead.

Dying Mystery Snail

If a Mystery snail is dying, it will often lie on the tank bottom, remaining inactive for hours on end, moving very slightly only occasionally. In rare cases, the snail might also lie inverted or upside down on its back.

Eventually, the snail might float around the tank, moving only very slightly every now and then.

Dying snails rarely hide inside their shells. In fact, Mystery snails regularly like to spend time away from the hustle and bustle of the aquarium community, retreating inside their shell for a few days just to get some peace.

Dead Mystery Snail

It’s time to be concerned when the snail starts to stink or feels lighter than its usual weight. In that case, the snail is usually deceased inside its shell.

So, basically, if the snail if moving very slightly by isn’t as active as usual, it’s probably dead. If the snail is totally inactive and smells revolting, it’s most likely dead.

What’s Wrong With My Mystery Snail?

If you think your Mystery snail is sick, how can you tell what’s wrong with the little guy?

Here’s an overview of the most common illnesses that can afflict Mystery snails.

Inflamed Foot

If your snail has a swollen foot, that usually indicates bad water quality in your aquarium.

It could be that you need to perform a partial water change to freshen the water in your tank, or perhaps your water filter media needs rinsing to remove any sludge that’s preventing the impeller from spinning.

If your tank water quality is okay and you have an old snail, the snail’s foot might swell because of the snail’s age. In that case, the snail will move around the tank on “tiptoe.”

Mystery snails only live for one or two years, so it could be that your snail is not necessarily dying but simply reaching the end of its natural lifespan.

Receding Osphradium

The snail’s osphradium is used by the creature to find food and is located inside the shell on the left-hand side.

A receding osphradium can indicate that the snail is dying, which is often the case in old Mystery snails.

Alternatively, the problem could be caused by too much ammonia in the water. In that case, you need to change some of the aquarium water and ensure your filtration system is working correctly.

Collapsed Mantle

A collapsed mantle is one of several snail emergencies. If your Mystery snail’s mantle collapses, the creature is near death, and there’s nothing you can do to cure it.

Floating Mystery Snail

A Mystery snail often floats when it’s sick since the creature is too weak to climb up the tank side for air. The snail pushes air in and out of its shell so that it can float or sink as required. Female snails often float after laying eggs because air gets into the shell when the eggs are laid.

However, that doesn’t always ring true, as these fascinating snails sometimes float simply because they can! If your snail starts floating, you must watch out for other symptoms that could indicate disease or illness.

We recommend leaving a floating snail alone, as the creature is probably fine. However, you should push the animal away from the filter inlet valve for safety.

Thin or Cracked Shell

If your Mystery snail develops a cracked or very thin shell, that means the creature doesn’t have enough calcium in its diet.

You can remedy the situation and recover the snail, but you must act promptly by adding a freshwater aquarium snail calcium supplement to your fish tank.

Copper Poisoning

If you keep your Mystery snails in a community setup that includes fish, you must know that many fish medications contain copper, which is absolutely deadly to snails and shrimp.

So, sick fish must be moved into a quarantine tank before treatment with any form of medication that contains even traces of copper.

How Can I Save My Mystery Snail?

mystery snail shell rot

If you think your Mystery snail is sick, what can you do to save your pet?

Change the Water!

Many people mistakenly think that because snails feed on detritus, they are fine in dirty water. However, as with aquarium fish, most problems with Mystery snail health are down to poor water quality.

The ideal water parameters for Mystery snails are as follows:

  • Water temperature 68 to 820 F
  • pH from 6.5 to 7.5
  • Water hardness between 7 to 18 dGH

You’ll need to carry out partial weekly water changes, replacing 20% of the water with fresh, dechlorinated tap water and vacuuming the substrate to remove excessive organic waste. Your Mystery snails won’t eat your aquatic plants, so you must trim off dead leaves and broken stems to keep the plants tidy.

Make it part of your regular routine to check the water in your tank every week with an aquarium water-testing kit so that you can make any adjustments required before problems surface.

Use Calcium Supplement

A cracked shell will allow bacteria to get inside the shell and attack the snail. Adding a liquid or powdered calcium supplement to the tank can help to keep the snail’s shell strong.

That said, you’ll need to ensure that any fish you keep in the same tank as your snails can tolerate harder water, or you could end up causing problems for your other livestock.


In this part of our guide, we answer some of the most commonly asked questions about mystery snails and their health.

Q: How Do You Save a Dying Mystery Snail?

A: Sometimes, a sick Mystery snail can be saved simply by carrying out a water change. Snails need clean water to remain healthy, just as fish do.

If your snail’s shell looks fragile or is cracking, providing your snail with a calcium supplement can be all it needs for recovery.

Q: Can a Mystery Snail Heal Itself?

A: If a snail has a damaged shell, the creature can often heal itself with the aid of calcium supplementation, as mentioned above.

There’s no need for you to intervene and try to glue the shell back together. Provided the snail hasn’t sustained any fleshy injuries or bacterial infection, it might make a full recovery.

Q: Why Is My Mystery Snail Lying on Its Side?

A: The usual reason for a Mystery snail to be lying on its side is that the snail is sick or dying. Although these snails sometimes float, which is normal behavior, a snail that’s upside down or on its side is generally sick.

Q: What Do You Feed a Sick Mystery Snail?

A: You shouldn’t assume that your snail will find all the food it needs in the fish tank.

Contrary to popular belief, Mystery snails must be offered foods to supplement what they can find in their immediate environment. Your snails will also enjoy sinking pellets, flakes, algae wafers, and fresh veggies as part of a balanced daily diet.

Q: What Is the Black Line on the Side of My Mystery Snail’s Shell?

A: If you notice a thin black line on the side of your snail’s shell on the same side as the whorl, that’s probably the snail’s digestive tract. You probably won’t notice that on a dark-colored snail, but the line is usually quite obvious on light-colored snails.

Q: Should I Get a Mystery Snail To Clean My Algae?

A: Unlike some snail species, Mystery snails should be offered foods to supplement their diet, as they can’t live solely on what they can scavenge in the tank.

In addition, Mystery snails are not voracious algae eaters since they don’t have strong enough teeth to rasp stubborn algae off the surfaces in your tank. That said, these snails will graze on the looser top layer of algae.

Q: Why Hasn’t My New Mystery Snail “Come Out” Yet?

A: If you have a new Mystery snail that’s still inside its shell and hasn’t emerged yet, you need to confirm that the creature is still alive.

Lift the snail gently out of the water and smell it. If the snail is dead, you’ll most likely be knocked sideways by the stink!

Put the snail in a container of tank water that just covers the creature, and float the tub of water in your tank to keep the water warm. That’s usually enough to persuade the snail to come out.

Final Thoughts

Did you enjoy our guide to sick Mystery snails and how to treat them? If you did, please take a moment to share the article with other snail fans!

Mystery snails are generally pretty healthy creatures that spend most of their lives foraging around the bottom of the tank, grazing on detritus and leftover fish food. These pretty snails will eat some algae, although they’re not voracious algae eaters and won’t harm your plants.

These snails have a short lifespan of between one and two years, and many of the sickness symptoms described above are directly related to old age. That said, snails are sensitive to poor water conditions, and medication containing copper can kill them.

Feed your snails a balanced diet and keep your tank clean with good water quality, and your Mystery snails should thrive!

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