Snails are indicators of water quality.If we observe a rapid rise in Planorbes and Melanoides tuberculata, it is because there is certainly water pollution or a sudden change in pH, a drop in hardness.

Anisus Vortex

Excellent algae fighter, never attacks healthy plants and eats dead leaves and dead fish. Has a very flat spiral shell. Anisus vortex is very small and dark brown in color reaching up to 1 cm.

The limnea are freshwater snails, measuring up to 2 cm adults so be careful with axolotls go fishing and of course rinse well everything you incorporate in your aquarium (plants, stones, etc.). Like land snails, they breathe through the lungs and must regularly come to the surface to breathe.
They mainly eat the microscopic algae and bacteria that proliferate on aquatic plants and walls. It also consumes algae or biofilms that form on the surface of stagnant eutrophic water. It consumes organic waste
The limneas feed mainly on plants. They graze on aquatic plants with a raspy "tongue", but in aquariums there are usually other food sources.

These animals are hermaphrodites, that is, they are both male and female.

The Planorbe ensures the maintenance of the plants by eliminating the necrotic parts of the plants. She will never poke holes in a healthy plant. A significant development of the population indicates an excess of food. The Planorbe has a lung, so it must rise to the surface regularly to breathe.

Planorbs are common freshwater snails in aquariums; they often arrive via aquatic plants and are therefore imported into the aquarium without the knowledge of the aquarist. These snails do not present a danger for the fish population, however, if the food ration distributed to the fish is important, the planorbes will know an excessive proliferation, they are then the sign and a bioindicator of pollution in the aquarium. The diet of these animals is mainly provided by algae, they consume green algae, diatoms, but also other microorganisms. They are described as detritivores.

Many consider them a plague, a nightmare for aquarists:
THE PHYSICS   (much smaller than limnea)
There are many aquarists who have chosen to put them in their tanks, they are found in almost all freshwater aquariums, most of the time they were introduced by buying a plant from a pet store.
It is interesting to observe them, these snails have lungs and thus need to go to the surface of the water to breathe.
They regularly lay small packages of transparent eggs on windows, plants, aquarium decorations, they are very prolific.
Depending on the temperature, the juveniles hatch after two to three weeks. They do not present any danger for the inhabitants of our aquariums, even the smallest, they are a good barometer of the balance of our aquarium: in too many they indicate an excess of food, at the top of the aquarium, on the water line they indicate an increase in nitrites.
(Article by Jérôme Muller)

Ferrissia (common name, freshwater limpet)

arrive with the plants. They are discreet because of their small size and do not present any nuisance in our bins, they look like the Chinese Hats of the seaside but in much smaller.
The shell is almost translucent white and slightly conical.
The body is rather in shades of gray.

Although belonging to the pulmonate family, respiration is essentially cutaneous. So they don't necessarily need to come to the surface to breathe.
Indicator of the absence of predation. Presence infrequent, often in young tanks.

Given the small size of this species, despite browsing windows or leaves of plants, no utility.
No nuisance in the aquarium.
Let's say that these animals are part of the microfauna that arouses little interest in general in our freshwater tanks.