Pros or cons of snails in aquarium

Is the evidence that snails, you keep in aquariums beneficial or harmful? Many beginner aquarists are wondering, what is the use of an aquarium snail and how to get rid of those snails that are harmful?Walking around aquarium shops, one can often hear seller say: “Buy snails – indispensable helpers that will make your aquarium perfectly clean.” Some say contemptuously: “Yes, all this is nonsense. There is more harm than good from them.
So who is right?

A description of the species and color forms

Despite the apparent primitiveness, the snail is a complex organism, whose life obeys its own laws. For most aquarists, snails are a purely secondary object (they seem to exist on their own), but, in my opinion, observing these animals is no less interesting than watching fish.

Amateur aquariums contain mollusks (type Mollusca), which are mainly classified as gastropods (Gastropoda). This class unites perhaps the most numerous and diverse group of species (about 80 thousand), whose representatives have mastered almost all corners of the globe both on land and under water.

Most often in indoor ponds, there are Spike-topped apple snail (genus Ampullaria), red forms of Physa  from Australia (Physa), and ramshorn snails (coils) from South America (Planorbis and Helisoma). So-called soil snails – melanias (Mclanoides), common from Egypt to Indonesia, are also frequent.


The body of the mollusks is enclosed in a protective calcareous shell of a spiral shape, the internal cavity of which serves as a reliable refuge for them. Looking at the aquarium snail, it seems that the shell for it is a heavy burden, predetermining the slowness of the mollusk. However, the weight of the shell is usually only 30-40 percent of the weight of the animal as a whole. By the way, in many mollusks, it is the shell that determines belonging to a particular genus and species. The color, structure, geometry of the spiral, the shape of the mouth, the location of the apex, and some other factors sometimes become decisive in the taxonomy.

The ramshorns coils are flat-screwed (the axis of the spiral runs perpendicular to the plane of the shell) and the apex is hidden inside, closer to the right (relative to the direction of movement of the cochlea, if you look at it from above) plane. From the left plane of the shell to the apex there is a funnel-shaped depression – the navel, in which various microorganisms settle.

In physa’s and melania’s, the conventional axis runs along with the shell, and the vertex is oriented back.

By the method of breathing, snails are divided into pulmonary and gill. Pulmonary, including coils and physicists, are forced to periodically rise to the surface of the water and swallow oxygen, which, depending on the composition of the blood characteristic of a particular species, is consumed longer or faster. But in any case, the periods between the “inhaling” of air are very long.

Gill snails (particularly melania) have fully mastered the process of utilization of oxygen dissolved in water, and do not need air oxygen. They spend most of their life on the ground and leave it when adverse conditions arise there. Some aquarists consider melania a good indicator of the gas state of the soil. However, it should be remembered that they also behave when changing atmospheric pressure, changing hydrochemical parameters of water, lack of feed, etc. So there is no need to talk about the reliability of this “alive signaling device”.

Scientists estimate that at one hour a snail (whether it is pulmonary or gill) consumes about 100 microliters of oxygen; it is much less than a small fish needs at the same time. Thus, even a fairly dense population of snails (especially those species that breathe atmospheric air) is unlikely to compete with aquarium fish.

Snail diagram

In nature, coils, and physa’s, as a rule, inhabit small sections of reservoirs with standing water, brightly lit by the sun and rich in the lower vegetation, which forms the basis of their diet. They do not disdain carrion, and with a shortage of feed, they can take over the young tender leaves of higher plants.

How to feed snails in an aquarium

In an aquarium, these snails, in addition to products traditional for them, eat any artificial food (including dry), as well as fish food debris. In this regard, snails are certainly useful because they prevent water spoilage due to food not eaten by fish.

(OMG) To Many Mystery Snails and Guppies
But the opinion that snails eat fish excrement is deeply mistaken. Even species that feed on detritus are not tempted by such a treat, presenting this honor to bacteria. So do not expect that the aquarium, even full of snails, will be free from metabolic products. On the contrary, like any other living organisms, snails themselves are actively involved in the “fertilizing” of the soil, which, if their quantity is excessive, can lead to excessive siltation.

It is not necessary to take seriously the statement that snails soften water since the calcium dissolved in water goes to build a shell. The fact is that this process is dual. On the one hand, living snails do utilize calcium salts, and on the other hand, the shells of dead mollusks, gradually dissolving, lime the soil, and therefore water.
Aquarium snails melania are very hardy and ductile. They can exist at a fairly wide temperature range (by the way, the optimum for them is 20-26 ° C) and other indicators, quickly adapting to new conditions. Possessing the ability to “seal” its shell, many species are able to survive for some time even extremely critical moments (being out of water, overheating, etc.).

I will give you an example. Once, when arranging a new aquarium, I decided to use part of the old soil, which was previously washed for several minutes with hot (about 60 ° C) water. Imagine my surprise when, after several weeks, I became convinced that small melanias live in this soil. They could not get into the aquarium with water or in any other way, and there were no plants there. So, they survived this “bath” in the ground and survived.

Ramshorn snails (coils) and physa extracted from water twist their body, compactly placing it in the upper part of the shell, and in this form, they can lie for several hours in a warm, dry place without any threat to life. Once in the water, the snails straighten and again return to their natural way of life.


Who eats snails in an aquarium

The enemies of adult snails in aquariums are fish. True, this applies mainly to large cichlids, tetradons, and some anabantoids, which have a large mouth and a powerful jaw apparatus.

And other fish tries to take advantage of the snail meat. But for this, the snail must behave extremely recklessly – stick himself out of the coil or stretch out his antenna sensors, which happens infrequently in aquariums (sometimes amateurs specifically grow snails in separate aquariums to further feed their fish with it). I must say that the reaction of these animals is surprisingly high: when the enemy approaches, they very quickly hide in their “house”.

Puffer fish eating tank snails
The total extermination of snails can result in the penetration into the aquarium of snail leeches of the genus Glossiphonia, which live in reservoirs practically throughout the world. Large size adult leeches (up to 3 centimeters long and 1 centimeter wide) enter the aquarium very rarely, but juveniles (one adult leech lays up to 200 eggs) are easily introduced from natural reservoirs along with food, other snails, water, etc.

The high chance of snail extermination is especially great during the period from June to July, when small leeches have already got rid of the mother’s guardianship (they are sitting on her abdomen in the first days of life), but have not yet become adults. Being formidable enemies of mollusks, they, however, do no harm to fish, so you can not resort to active struggle with leeches. Having destroyed the population of snails, they remain without food and soon die themselves.

Despite the general physiology, aquarium snails of different species are far from similar in everything. So, physicists prefer brightly lit upper horizons of water. They are inactive and may not leave the limited area of ​​the aquarium they have chosen for days. Bundling in thickets of riccia and other floating plants, aquarium snails physis freely move from bush to bush along the surface film.


Ramshorn snails coils can live in any layers of water, but try to avoid places where physa are. They move quite quickly (compared to physicists they can be considered sprinters), but at the same time they maintain smooth movements.
Melanias inhabit the soil, actively draining it in search of food. With the help of their trunk-like mouth, they remove food from the narrowest slots. They don’t like the light, the maximum activity falls on twilight and night time. They move in jerks – first they stretch the leg, then pull the shell with the body. The speed of movement of grindings is largely determined by the composition of the soil: the larger and heavier its fractions, the more difficult it is for the grindings to “drill” it (although they are able to move a stone two to three times their weight). At the same time, they avoid fine-grained, poorly ventilated soil.

Breeding of aquarium snails

Snails differ in the method of reproduction, although the vast majority of freshwater “lungs” have a common feature – hermaphroditism. But for breeding, one individual is not enough, since for these snails cross fertilization is characteristic.
Physa and coils lay eggs in the form of compact clutches with a common shell.

Very interesting video of a snail laying eggs in an aquarium:

Aquarium Snail Laying Eggs [Time Lapse]
Physa eggs has the appearance of a sausage curved in a half-ring and usually consists of several tens of eggs. They are placed in layers in a plastic gelatinous substance surrounded by a soft shell. Almost any surface can be a substrate.
It is very easy to separate the eggs from the substrate, while the development of embryos (if the outer shell of the masonry is not damaged) is not disturbed. Newborn snails leave the egg shells after 4-6 weeks, depending on the temperature of the water. If you remove the clutch from the water, it dries within an hour and the snails die.

Ramshorn snails prefer to lay eggs on a soft or rough substrate (plant leaves, stone surface, etc.), avoiding placing the laying on glass. Laying with a height of 2-3 millimeters has the shape of a cake with an oval or round base with a diameter of about a centimeter.

It is strong enough, tight, and fairly firmly adheres to the substrate. The eggs are located in the same plane. Their number is from 10 and above – depending on the age of the individual. Under a strong magnifying glass or a microscope, it can be seen that the structure of the laying resembles a honeycomb.

The development of larvae lasts 3-5 weeks. It is curious that almost from the very beginning they lead a rather active lifestyle, constantly moving inside the egg. Gradually, the intensity of movement increases. After 5-6 days, the larvae become like parents. Even with a not very large increase, you can see the leg, tentacle sensors, and other characteristic organs, including some kind of shell.

Eggs of snails and especially young snails hatched from them with a shell still not strong enough easily become prey for fish. Therefore, populations of physa and coils rarely reach the number at which the natural course of biological processes in the aquarium is disrupted.

If necessary, part of the snails can be caught using tweezers. If you want more in the aquarium, you need to select 5-6 large individuals and put them in a separate jar. You can place it in any place where the water will not overheat or supercool. Once a few days, a little amount of food should be thrown into the water (dry fish food, rotten leaves of plants, etc., are quite suitable).


In a jar, you need to put a couple of flat pebbles and several large leaves of aquarium plants (you can already begin to decompose), which will serve as a substrate. Soon, on the walls of the jar or on the surface of the substrate, numerous snail egg layings will appear, and after a certain time, young snails. When they grow up a little and strengthen their carapace (2-3 weeks are enough), they are carefully collected from the walls with a piece of cotton wool or a cloth (it’s easy to crush them with your fingers or tweezers) and brush them into the thicket of plants in the aquarium. Melanias are viviparous snails.

Since they spend most of their life in the ground, and in the absence of it they die quite quickly, very little is known about the biology of their reproduction. It is impossible to control the number of these snails in the aquarium. Since adults are well protected from fish by a solid shell, and young ones by a layer of soil, sometimes it comes to the point that the population grows to enormous size, especially with an abundance of food. In such an aquarium, pebbles or grains of sand constantly move. I must say, the picture is not pleasant.

You can deal with an excessive amount of melania without disturbing the other inhabitants of the aquarium in a very primitive way – periodically catch large specimens. If you are so intolerant of snails that you are ready to temporarily remove all fish and plants from the aquarium, then you can use a more radical way: cool the water to 15-16 ° C or add chemical preparations (copper sulfate, etc.) to it.

Under favorable conditions, snails in aquariums live for about 2-3 years, growing to maximum size. The diameter of the shell of the coil can reach one and a half to two centimeters (usually no more than one) with a width of up to 0.4-0.7 centimeters. For physa, the shell can have up to one and a half centimeters in length with a diameter at the entrance of 0.5-1 centimeter, but usually less. The length of the melania shell is sometimes 2-3 centimeters with a maximum diameter of 0.5.

By old age, mollusks lose their attractiveness. For many, the last turns of the spiral (at the mouth of the shell) are deformed, and the random pile of calcareous layers does not decorate them at all.


Now back to where the article started: are snails in an aquarium harmful or beneficial? Neither one nor the other. They are simply equal participants in the aquarium biocenosis. In a common decorative pond, they are perhaps even useful. The only exception is melania, and even then only in frame aquariums with putty based on drying oil and cement (now such a sealant is almost never used). Newborn melanias crawl into the smallest gaps formed in the putty and, developing there, accelerate the destruction process. To prevent this from happening, it is better to additionally cover the joints of the frame aquarium with a layer of silicone glue or other sealants (sometimes snail clay used sometimes is quickly eaten, exposing the seam).

If you prefer video information more, look at this one. Video authors tells his personal story of having snail in the aquarium: Be careful this video has SOUND!

Aquarium Snails Good Or Bad? - The TRUTH REVEALED
The situation is different with specialized reservoirs. In particular, mollusks are undesirable in aquariums such as the dutch types, because with a shortage of feed they can damage (but not destroy) the leaves of plants, which will reduce the decorative value of the reservoir. They are not needed in aquariums where herbivorous fish live – their competitors.

The presence of snails in spawning and caviar incubators are in danger: with sharp and rough edges of the shells, they damage the shells of eggs.
But in a growing aquarium, snails become your helpers, eliminating the tedious need to “siphon” the bottom after each fish feed (this, however, will not completely free you from cleaning the reservoir, since it will increase the amount of organics that must be removed periodically).

As you can see, there are very few troubles from snails, but almost no use. You do not have snails – and do not. And if there is, watch their life, these animals are very attractive.