Mystery snails (commonly called Apple Snails, the scientific name is Pomacea Brigesii / Pomacea diffusa) are peaceful, herbivores, slow-moving freshwater snails which are popular in the aquarium hobby for the right reasons. They clean up excess food, waste and eat algae from the aquarium decor, gravel, glass, and plants.
This guide will teach you more about keeping Mystery snails plus better ways to take good care of them, including their compatibility with other types of species, breeding, and appearance. I will show you the results of the experiments, provide useful information, give some tips, and that is all in one place.
However, before that, I need to point out that there are different species in genus Pomacea, which are also commonly referred to as “Apple” snails. Unfortunately, most of them are the pest species, which should be avoided.
Quick Notes about Mystery Snails
|Common names||Apple snail, Spike-topped apple snail, Miracle snail, Golden snail, Cherry snail, Inca snail.|
|Scientific name||Pomacea Brigesii / Pomacea Diffusa|
|Tank size (minimal)||5-gallons (~20 liters)|
|Size||4.5 – 6.5 cm (1.7 – 2.5 inches)|
|Temperature||20 to 28 C (~68°F – 84°F)|
|Optimal PH||7 – 8|
|Optimal GH||7 – 18|
|Optimal KH||8 (3 -18)|
|TDS (optimal)||100-250 (100-400)|
|Nitrate||Less than 20 ppm|
|Temperament||Peaceful and solitary|
|Life span||1 – 3 years|
|Color Form||Species-Dependent (huge variety of colors and patterns)|
Pomacea Brigesii/Diffusa (good snail) vs Pomacea canaliculata (pest snail)
Please, do not skip this paragraph, otherwise, you risk finding your beautiful planted tank completely annihilated.
As I have just said, the genus Pomacea includes lots of the pest species. These species have been introduced outside their native ranges and have become serious agricultural pests. There are many examples of ampullariids causing damage to crops, predominantly wetland rice, in their native ranges and USA.
At least three exotic species (Pomacea insularum, Pomacea canaliculata, and Marisa cornuarietis) are even invasive pests. In fact, Pomacea canaliculata is on the list of the world’s worst 100 invasive alien species (and top 40 in Europe.), due to their potential effect on the ecosystem and huge economic losses especially in Asia.
For instance, Pomacea canaliculata feed voraciously on aquatic vegetation, and high population densities can result in the consumption of the entire aquatic plant within very short periods. In addition, they even fail to eat algae, which is quite important for the aquatic hobby.
Regulatory changes have banned live Pomacea spp., with the exception of Pomacea bridgesii ([often a misidentification of] Pomacea diffusa), from any United States trade.
Unlike Pomacea canaliculata, Pomacea bridgesii and Pomacea diffusa does not feed on plants but does eat algae. As a result, these types of Mystery snail became the primary snails in the American aquarium industry.
Taxonomy problems of Mystery snails
Pomacea bridgesii (Reeve, 1856) and Pomacea diffusa (Blume, 1957) have long been considered to be a single species. However, according to recent DNA analysis, nowadays, scientists consider them to be distinct species.
Pomacea bridgesii is a relatively rare species (in aquarium hobby) that is known to inhabit a small range: the Rio Grande, Reyes River at Beni. Pomacea diffusa is much more common and inhabits almost the entire Amazon river system. As a result, Pomacea diffusa is more common in the aquarium trade.
Regarding the appearance, the main difference is the size. Pomacea bridgesii is a little bit bigger compared to Pomacea diffusa.
Why are these snails called Mystery snails?
There are few theories about that and the one I like the most is that when the pet-stores first started getting them to sell, they had no clue what kind of snails they were. Some of those snails could completely destroy the planted tanks while others were great at algae cleaning.
Aquarists got really confused. Therefore, they simply called them – Mystery snails. In reality, nobody knows for sure. It is a mystery. 🙂
Overview of Mystery snail
They are common in Brazil, Paraguay, and Bolivia. Natively, they are found in rivers, swamps, and ponds where they can easily eat dead and decomposing plants.
These snails live up to 3 – 4 years in the wild and eat dead plants while at the same time cleaning the environment. This enables all nutrients ensnared in detritus to get back into the ecosystem.
These snails are loved for their beautiful colors. They are very peaceful, which makes it safe to keep them together with plants, shrimp and fish. What makes them unique from other types of snails is their way of breathing and their breeding methods. They can breathe via a tube which extends from the front side of their bodies or even breathe via gills.
Respiration of Mystery snail
Mystery snails are amphibious. Juveniles and adults use both aerial and aquatic respiration, allowing them to inhabit waters low in dissolved oxygen and to withstand some crowding, which can be important during shipping and wholesale stocking.
They have in their mantle cavity both a gill on the right side of the mantle cavity and the lung (pulmonary sack) on the left side. The lung is used for aerial gas exchange while the gill is used for aquatic exchange. This ability to use both lung and gill allow Pomacean snails to survive in conditions of aerial exposure and during low oxygen conditions.
Direct pulmonary respiration occurs when the snail leaves the water. In Mystery snails, lung ventilation is obligatory, so they regularly come to the surface to take a breath. They extend their tube above the water and take in air by moving back and forth.
Note: Sometimes aquarists confuse the reproductive organ with the lung. It is possible to see it on the left side of the snail (sticking out). Their sex organs are much further into the body and you have to wait for them to move a certain way to be able to see it.
The Behavior of Mystery snail
They are very peaceful in that if they are attacked by an aggressive fish, all they will do is hunker down to hide inside their shell. It is crucial to ensure that they are kept with peaceful fish so that they aren’t scared most of the time and that they become active and clean the tank effectively.
Mystery snails are pretty quick for the snails. Although they are still pretty active during the day they are more active at night. Basically, they prefer more a dim light.
If you have an escapee or if they have been out of the water several hours they will retreat inside their shell and look dead. Do not throw the snail away. Put it back to your tank and there is a high chance that the snail will pop back out.
Mystery snails can float. They go to the surface and form a funnel with their foot in which they let the water from the surface flow through.
If you have a sand substrate, they may burrow in the sand.
Note: From time to time, Mystery snail can climb to the tank’s top and fall to the bottom of the tank. Luckily, you do not need to worry if they fall on their back because they can flip themselves over.
The Appearance of Mystery snail
The snails have a variety of colors where the most popular colors are gold, blue, purple, orange, dark greenish, black, white, ivory, albino (white body with brown strips) and brown variants. Their shells have different patterns as well.
All in all, they will add a beautiful touch to freshwater tanks.
Mystery snails are a large species. The shell differs in size from 40 – 50 mm (1.5 – 2 inches) wide and 45 – 65 mm in length (1.7 – 2.5 inches) in diameter.
The moment people think about snails, they tend to think of the entire spiral whorl from the apex expanding downwards towards the opening or aperture. Although the shell may be extremely variable, in general, the whorls of Mystery snail have a distinctive stair-like appearance (it is like 90 degrees). The spire is sharp and high and has about 5 to 6 whorls.
The top of Mystery snails is more towards the side of their opening. The head has two big tentacles to help them find food and sense the environment. Their eyes are directly behind their tentacles. The eyes detect light and motion. There are no sensory organs positioned in the cephalic eyestalk apart from its eyes.
The operculum is the other part of their structure and is the place utilized to close the shell’s opening. This is a nice way to see whether your snail is healthy and alive. The operculum falls off as soon as the snail dies but will not close properly if there is something wrong with that snail.
Mystery Snail Diet
Like many snails, Mystery snails are naturally optimistic scavengers and not fussy about what they eat. Naturally, they will eat almost anything, dead fish, dead shrimp or shellfish, dead or rotting plant matter, algae, and anything else they find.
Due to this, keep a high or medium level of vegetation to give the snails a natural source of food. As plants grow, they shed leaves which give snails the best food in addition to algae.
I would like to stress that these species prefer decomposed animal food or dead and rotting plants rather than fresh green ones. Mystery snails do not show any interest in any of the aquatic plants as a food source and can even starve if no other food is provided. These snails are thus a good choice for an aquarium
Mystery snails eat algae on aquarium glass, sand, and rocks, which grows on it. This is why people use the snails to keep the glass clean for a longer period, meaning less work for you. You can see the snails’ tracks as they graze and move around.
Adding supplements such as flakes, feeder tablets or pellets to their diet keeps them healthy and enrich the diet. They love softly blanched vegetables (read more about it in my article “How to Blanch Сucumbers and Zucchini for Shrimp, Snails and Fish the Right Way”).
No matter what you feed, the one thing they must have in abundance is calcium, both dietary and in their water.
Snails and Calcium
People lose a lot of snails and do not realize what was the problem. Actually, it concerns all types of snails.
One of the main reasons is the lack of calcium in the water. Do not forget that their shells are made of it. Therefore, you need to give them calcium in many different ways. For example, you can use wonder shells, which can easily be broken into pieces. You can also add crushed coral to increase the hardness of the tank and then just feed a diet that is high in calcium.
Foods such as blanched spinach, kale, or broccoli are also a good source of calcium. A lot of aquarists use cuttlebone for the water. Cuttlebone is all calcium. Put it in the tank and after a while it will sink. Cuttlebone will release calcium into the water and the snails will chew on it.
How much should you feed Mystery snail?
To my surprise, I saw multiple recommendations that for optimum health, you need to feed your snails as much food as they will consume in 1 – 3 minutes. Well, let me strongly disagree with that. I believe that this is totally wrong!
Mystery snails are big snails and they require a lot of food. I mean really a lot! Ideally, they should always have something to chew (at least algae). I feed enough at one time so that it takes them at least several hours to eat it. However, if there are still leftovers 12 hours later, then you should feed less of that food next time. They simply cannot eat fast. Lots of aquarists reported that they do not breed well without enough food.
Another interesting and fascinating thing about this species is their digestive tract. Mystery snails they have a very inefficient digestive tract and tons and tons of microorganisms in their intestines. Those microorganisms stick in their feces, which then gets stuck in their slime, which is spread all over the aquarium.
I know that it sounds pretty disgusting until you think about a bit further. In fact, this partially digested food is actually a phenomenally excellent food for fish fry or shrimp. It is one of the main reasons how snails can benefit, for example, a shrimp tank (you can read my article about “Benefits of Snails for a Shrimp Aquarium”).
Mystery snail and Tank Conditions
Mystery snail is very adaptable. For example, according to some experiments, the upper lethal temperature for these snails is about 40°C when snails are exposed for 1 – 4 hours, while this species can survive at 10°C. They go into hibernation mode in really cold water.
Although they primarily live in fresh water, they also exhibit some tolerance of salinity. For example, Pomacea bridgesii exhibits tolerance for salinity levels ranging from 0-6.8 ppt in which the probability of survival is higher than 80% after 3 days of exposure.
Nonetheless, let’s not talk about the extreme environment because it is quite obvious that they will not thrive and reproduce there.
Mystery snails will enjoy highly oxygenated, moderately moving waters, which is why they are put in tropical community tanks. The water should have a pH level range of 7.0 to 8.0, a temperature range of 68F to 84F (20 – 28 С) and the water type should be from around 8 KH.
Snail shells are comprised of 95–99.9% calcium carbonate. Low pH levels dissolve the available calcium carbonate in snails shells, which leave the snails open to harm from fish. Thin, pitted, pale and cracked shells indicate low pH and low calcium levels. Add some calcium supplements to ensure they have healthy and strong shells.
Using a fitting lid ensures the snails do not crawl away.
Although they can live in almost all size tanks, it is recommended to keep them in 10-gallon tanks. They spend much of their time moving around, so the more surface area available, the better.
Like shrimp, Snails are super sensitive to copper (read my article about “How Copper Affects Dwarf Shrimp”). Watch out for signs of copper especially if you have tap water in your tank.
Note: Mystery snails are usually hardy by nature; however, avoid rapid changes in water conditions.
Mystery Snail Mating
There is no visible sexual dimorphism, but in all copulations observed, males were smaller in size than females. Nonetheless, this method is not completely reliable. It is very easy to confuse. Therefore, if you are planning to breed them, you will need a group of 5 – 6 to improve the odds of getting both genders. Of course, you can be lucky with just two of the same species.
According to observations, the male snail usually approaches the female from behind, crawls over her shell and when at the last whorl searches for the genital aperture, grasping with his penial sheath, and inserts it.
Copulation can last for 1 – 5 hours and during this period the female usually crawls around feeding, while the male retracts inside his shell. The pair can be even lifted out of the water without interrupting copulation, showing that the male is firmly attached to the female during the entire copulation period.
Note: Females can store sperm for months. Therefore, she can continue to lay eggs for quite some time.
Mystery Snail Breeding
They will mate without help or any altered tank conditions. The female lays eggs masses above the surface of the water and leaves them in a cocoon for them to spot the eggs easily. In the wild, this remarkable strategy protects their eggs against predation by fish and other water inhabitants.
The oviposition of a single egg clutch occurs predominantly at night or in the evening. Each egg clutch can contain between 50 – 200 eggs, depending mainly on female size.
Oviposition is difficult to observe since it usually occurs at night. The female crawls from the water and deposits eggs on the tank wall. The eggs slide, one by one, from the mantle to the lower edge of the clutch. The female descends the glass backward while depositing the eggs and, when finished, simply lets herself fall down into the water. Freshly-deposited egg-masses are soft, milky pink and conspicuous.
After 24 hours the eggs become white and harden. At the lower edge of the cluster eggs usually show the soft, milky appearance. The egg clutches have a calcareous covering, which might be used as a source of calcium for developing the embryo.
The air surrounding the cocoon above the water should be moist and the eggs are expected to hatch in 15 – 24 days after oviposition at 23.0ºC. (The higher the temperature the faster they will hatch). Hatching can last up to 20 hours in the same cluster.
Note: If, after 3 – 4 weeks, you do not see any dark spots (these are baby snails inside the eggs), then you can remove the clutch.
Development is direct and juveniles hatch at shell length 2.4 mm. Recently hatched juveniles are similar (tiny copies) to adults. The hatched snails fall to the tank’s bottom to begin their lives and eat the same food just like the parents.
Tip: In order to breed, lower the level of water 3 – 4 inches (7 – 10 cm), so that there is sufficient room for laying eggs.
Note: According to some experiments, newly hatched baby mystery snails are heavily depended on algae in the tank. For example, the survival during the first 8 days of juvenile life was 90.8% if the only algal film was available, 88.9% if the algal film and crushed food were available and 64.4% if only crushed food was provided.
Tip: You need to have a tight-fitting lid otherwise it will not stay humid if it does not stay humid the eggs dry out.
Interesting fact: Mystery snail has been reported to gain weight rapidly (1.7% per day at 27.6 ˚C under laboratory conditions. It is pretty fast, especially in the first four to six weeks. They can reach 1/2 to 3/4″ within 5 – 6 months or so.
Mystery Snail and Tank Mates
Mystery snail is a solitary snail. They do not care much about other snails in the tank. These snails will not bother anybody and prefer to mind their own business.
Due to their peaceful nature, it makes a lot of sense if they are kept together with tank mates that are equally quiet and peaceful. For example, Japanese trapdoor snail, Ramshorn snail, Nerite snails, Malaysian Trumpet snails even Rabbit Snail.
Concerning the fish species and some natural enemies, Mystery snail should not be kept with Botia lohacata, Cichlids, Loaches and Goldfish. Also, keep Mystery snail away from all types of Crayfish and even some types of predatory shrimp such as Macrobrachium family. All of them can be very aggressive.
Keep in mind that some fish do not feed on the snails but eat the exposed eyestalks or tentacles tissues. Ensure you detect this kind of damage to the mystery snails for them to be removed.
Mystery snails (Pomacea bridgesii and Pomacea diffusa) with their different coloration and large size, along with their ability to eat encrusting algae and dead animal matter are attractive as both ornamental and cleaning species in aquaria. They are just so fascinating and adorable.
If you are considering having Mystery snails in your tank, ensure your tank has plenty of vegetation and peaceful invertebrates and fish. These snails are very easy to keep since they do not require you to do much to keep them alive.
These species are plant safe. Actually, they tend to starve to death in the middle of the vegetation if you do not provide them with enough food.
Mystery snails are good for both experts and beginners and that’s why they’ve become one of the most liked freshwater snails and popular aquarium pets all over the world.
Due to their popularity among aquarists, it is important to use the following common rule before purchasing snails to put in your tank. Take some time to observe the snails in the store and go for the ones moving or those attached to a surface. Be keen not to purchase a snail, which has a damaged or cracked shell.