Care Guide for Mystery Snails — Entertaining and Useful Scavenger

Many aquarium hobbyists don’t like pest snails like bladder, ramshorn, and Malaysian trumpet snails because they can rapidly increase in population even if you only start with one. In contrast, mystery snails (Pomacea diffusa and P. bridgesii) are really cool, little pets that you can buy at your local pet or fish store for only $3–4. They cannot self-fertilize or change their sex, which makes it much easier to control their breeding, and unlike their larger apple snail relatives, they won’t eat your plants. Find out why this bold and colorful invertebrate is such a joy to own and how to best care for its needs.

What are Mystery Snails?

Compared to its cousins, the mystery snail or spike-topped apple snail has a pointier tip to its shell and stays smaller at around 2 inches (5 cm) in diameter. The shell comes in many colors — like golden yellow, blue, magenta, purple, ivory, chestnut brown, black, and jade green — and the foot can be either light- or dark-colored. These excellent scavengers love to clean up your aquarium by consuming excess fish food, deceased animals, and dead leaves so that they won’t foul the water. If you see your mystery snail “eating” a healthy plant, most likely they are actually nibbling on melted or sickly leaves for you. Some hobbyists find them to be hardier but not as good at algae eating as nerite snails.

They are very active and faster than most snails, so you will find them climbing all over the tank. They have many fascinating behaviors, such as when they extend their long breathing siphon from the left shoulder. They possess both gills and lungs that allow them to breathe while out of water. Holding air in the lungs causes the snails to float, while releasing the air causes them to drop or “parasnail” down to the ground. Thankfully, mystery snails can easily right themselves if they land upside-down, so usually there is no need to help them.

How can I tell if my snail is dead? Sometimes it can be hard to tell if your snail is sleeping or deceased. If it has not moved in 24–48 hours, consider picking it up to see if it reacts. If you detect an overpowering stench, then unfortunately it has passed away. The mystery snail has an average life span of 1–2 years, depending on the water temperature. Keeping the water on the cooler side may slow down its metabolism and increase its longevity.

Mystery snail climbing on the aquarium glass

How to Set Up an Aquarium for Mystery Snails

Although mystery snails come from South America, they cannot live in soft water environments. They require lots of calcium and other minerals in their water and diet to grow a healthy, smooth shell. If you see pits and divots in your snail’s shell, try dosing mineral supplements such as Wonder Shell and Seachem Equilibrium. Their ideal parameters include temperatures of 70–78°F (21–26°C), pH of at least 7.2, and GH above 150 ppm (or 8 degrees). Because of their size, one or two mystery snail can live in a 5-gallon aquarium or larger with a tight-fitting lid that prevents them from crawling out. They are safe to keep with aquarium plants but may accidentally uproot new plants in loose substrate when they crawl past them. As with most snails, they are sensitive to salt and copper-based medications, so please remove them if the aquarium is being treated with those chemicals.

What fish can live with mystery snails? As a peaceful invertebrate, they can live with many other community fish that are also compatible with higher pH and harder water. Naturally, do not keep them with snail eaters like puffer fish, certain loaches, and turtles. Also, avoid any fish that may try to nibble on their long antennae, which kind of look like small worms. In the past, we have kept them with dwarf shrimp, tetras, kuhli loaches, corydoras, calmer betta fish that aren’t as aggressive, and many other tank mates.

Mystery snails of different colors

What Do Mystery Snails Eat?

As scavengers, they are not picky eaters and will eat way more than you think is possible. Their diet in an aquarium usually consists of fish food, algae, biofilm, dead fish, and dead plants. The one exception to the “mystery snails don’t eat healthy plants” rule is duckweed. There are many recorded accounts of mystery snails eating duckweed and other small floating plants, so if needed, consider putting your floating plants in a floating container to protect them.

In order to eat from the water surface, mystery snails can form a funnel-like shape with their foot to gather floating foods like fish flakes. However, they usually eat off the ground or from flat surfaces. To ensure they get plenty of minerals in their diet for strong shell growth, we like to feed Hikari Crab Cuisine, shrimp foods, nano banquet food blocks, and calcium-rich vegetables like blanched spinach or kale. An easy way to make your own “snello” or snail jello food is to make Repashy gel food mixed with calcium powder or crushed, unflavored calcium carbonate antacid tablets (like Tums).

How to Stop Mystery Snails from Breeding

The interesting thing about mystery snails is that they will not reproduce under water. They actually lay their eggs above water to prevent predators from eating them. Therefore, if you wish to stop them from breeding, here are a few tips:

• Only get one mystery snail per aquarium. Since each snail has a single sex (i.e., male or female) and cannot change sexes, keeping them solo will prevent procreation.
• Females can store sperm for long periods of time, so buy a snail that is under 1 inch (2.5 cm) in diameter. Usually, juveniles of that size are not sexually mature yet.
• Keep the water level in the fish tank within 1.5 inches (4 cm) or less from the top so that they do not have room to lay their eggs out of the water.
• If they are clever enough to lay their eggs on the aquarium lid or hood, make sure to remove the egg clusters before they hatch.

Pink egg clutch full of mystery snail offspring

How to Breed Mystery Snails

Like most fish, you must have at least one male and one female mystery snail in order to breed them. However, sexing can be very difficult to do when you’re at the fish store because it takes a lot of patience and luck. Hold the snail in a vertical position so that you can look straight into the shell opening and wait for the snail to right itself by extending the foot. This process can take anywhere from 5–30 minutes or more. If the snail stretches out at the correct angle, you may be able to see their “shoulder” regions inside the shell. Females have two holes, one over each shoulder. Males have one hole over the left shoulder, but the hole over the right shoulder is blocked by his reproductive sheath. Another technique for sexing the snails is to watch for two snails mating — the male will be the snail on the top. However, the simplest method is to just buy a group of six or more snails so that you have a very high likelihood of getting both sexes.

To condition them for breeding, gradually increase the amount of food you are feeding them. Drop the water line by at least 3–4 inches (8ؘ–10 cm) from the top to give them plenty of space to lay eggs. Younger females may lay 50–100 eggs, while bigger, mature females can lay hundreds of eggs. The clutch looks like a giant, elongated blackberry that is pink in coloration. Make sure you have a tight-fitting lid so that the eggs are kept warm and humid. Otherwise, the egg casing will harden and dry out, preventing the babies from hatching. Depending on the temperature, the baby snails will be ready to hatch within 1–4 weeks and come out looking like miniature adult snails. They will chew through the egg casing wall and drop into the water, ready to begin their new life in the fish tank. Make sure the aquarium has a sponge filter or pre-filter sponge over the filter's intake tube, or else the tiny babies may inadvertently get sucked up.

If you do not have an aquarium lid or want to increase the survival rate of the babies, you can hatch the eggs in a separate container. Let the egg clutch harden for 1–2 days after being laid, and then gently remove it from the tank with your hands. Wet one sheet of paper towel in tank water and squeeze out the excess moisture. Get a plastic Tupperware container and fold the damp paper towel so that it fits inside and completely covers the bottom. Place the egg clutch in the middle of the damp paper towel, and then place a couple more sheets of dry paper towels on top of it. Drill or poke a few holes into the plastic container’s lid and close the container to maintain high humidity. Open the container once a day to wipe off any excess moisture from the lid and replace the topmost paper towel if it gets too wet. When the eggs are ready to hatch, the clutch changes from pink to a moldy, whitish-gray color. This is completely normal, so do not throw away the clutch. Instead, get a floating breeder box and place it in the aquarium they will be living in so they can get used to the water parameters. Gently rub the egg clutch to free the babies and break apart the clutch. Leave the clutch remnants inside the container in case any babies have not hatched yet. The hatchlings are very small and can accidentally get vacuumed up by an aquarium siphon, so keeping them in the breeder box will help protect them and make it easier to feed them so that the babies don’t have to travel as far to find food. (They can eat most of the same foods as the adults.) Plus, after a few days you should be able to see what colors the babies are and decide which ones you want to cull or give away. Once the babies are the size of a pea, they can be released into the main tank. 

Adult and baby mystery snails

If you find that you are breeding too many mystery snails, you can always use the techniques described above to stop the breeding, feed the excess to your snail eaters, or sell some to your local fish store or hobbyists. To get your own mystery snails, check out our preferred online retailers to see what colors they have in stock.