Melanoides tuberculata is one of the most commonly kept snails. Or rather, it is one of the species most often present in the aquarium – often it finds itself there without the aquarist’s knowledge.
It is a very specific aquarium inhabitant, spending most of its time buried in the substrate and rarely venturing out to explore the aquarium. We can have hundreds of these snails without even knowing it. And few people probably know that apart from “plumping up” the substrate in aquariums all over the world, this species is also interesting in many other ways.
The tower darter, as Melanoides tuberculata is called in Czech, is not a close relative of any other species kept in aquariums. It belongs to the family Thiaridae and is sometimes found under the synonyms Nerita tuberculata, Thiara tuberculata, T. tuberculatus or Melania (Melanoides) tuberculatus.
Its home range is in tropical and subtropical Asia and Africa, ranging from Morocco through Madagascar, Saudi Arabia to southern China, Java and Celebes. Today, it is virtually cosmopolitan, or everywhere in the tropical and subtropical zone; it has appeared in Israel, Hawaii, Polynesia, Australia and New Zealand, the southern USA, Mexico, Puerto Rico, Panama, Venezuela and Brazil. It has been introduced to most of the new areas by aquarists.
It inhabits stagnant and slow-moving waters, especially those with muddy or sandy-muddy substrates, where it can occur in incredible abundance (e.g. up to 37 500 individuals per square metre have been found in coastal stands in Florida). It can tolerate salt water up to 30 mg/l. It requires warmer water, but in Israel, for example, it survives the winter buried deep in the mud.
It usually grows up to 2 cm in size, but in the wild it can grow up to four times that size. Its five-threaded shell is massive and hard, decorated with various ornaments (populations from different parts of the world differ from one another). It also has a tiny dark cap (operculum). It breathes only through the gills. You will not confuse the Piscora with any other species in the aquarium, its appearance and behaviour are completely unique. It also has a beautiful head shape and beautiful eyes – but these are rarely seen.
Melanoides tuberculata is more or less a nocturnal creature. During the day, it hides in the substrate, crawling around looking for something to eat. In doing so, it prevents it from sloughing off and forming anaerobic zones. Occasionally, the gravel in the aquarium can even be seen to lift and shift strangely.
The gravel does not damage the roots of the plants or their green parts. It feeds on dead material, various debris, and possibly consumes algae during its nocturnal excursions off the substrate.
In the event of a lack of oxygen in the aquarium, it can be seen on the glass as they head straight for the surface in large numbers. Such a mass escape is always a signal of some water or filtration problem. Of course, overpopulated snails that produce waste also contribute to poor water quality.
Melanoides tuberculata is a hermaphrodite and also reproduces parthenogenetically – that is, mating with another individual is not necessary for reproduction, each one is on its own 🙂 Thus, a single stray pipefish can fill the aquarium with its offspring. In addition, there is also “normal” reproduction with the sexual union of two individuals.
The Piscora is viviparous, carrying a pouch with the developing young in the head section, or supposedly also outside on the shell. Freshly born snails measure about 2 mm and are faithful imitations of their parents (or parents if they have only one). They breed as young as 1 cm. The number of young usually varies between 1 and 70.
Melanoides tuberculata reproduces very quickly under the right conditions (warm water and, above all, plenty of food…. overfeeding fish!!!) and we may not even notice it. If there is a massive overpopulation at night, the snails cover glass, all decoration and plants (the reward is that they keep all surfaces free of algae); we often see them during the day and the gravel is in constant motion, making it difficult to plant new plants. They also get into the filter in large numbers, which can cause problems.
In such an extreme case, their numbers must be reduced. They can easily be collected from the glass, or some ‘snail-eating’ fish can be introduced. It is true that due to their hidden way of life, fish active at night or species that are strictly focused on searching for snails, such as quahogs, have a chance to enjoy them. But beware of the particularly hard shell of the lamprey! There have been cases of damage to the jaws of puffins, which eventually led to their death. So, if you want to keep a quatrefoil (I definitely don’t recommend putting them in a community aquarium), you’d better remove all the lampreys from the aquarium beforehand. On the other hand, good experiences have been had with botia, which can handle these snails. Predatory shrimps of the Macrobrachium genus will also enjoy them, and will pull the lamprey out of its shell (but then again, these little creatures will also enjoy fish!). The hard shell will otherwise protect the lamprey from African cichlids. My “snails” are constantly carrying sand and throwing away the smallest speck of sand from the surroundings of their house, so this is how they move the piskerfish every now and then. However, the snails are not harmed and thrive in the tanganic habitat.
Melanoides tuberculata often becomes a pest in places where it has been introduced. It competes with local gastropod species and can negatively affect their abundance or even cause their disappearance. It also hosts some parasites that can potentially threaten humans, including bile and lung flukes. To complete the life cycle of the parasite, the gastropod must first become prey to a fish (or crustacean), which must then be eaten by humans when undercooked. The result of all this is then liver or lung dystomatosis.
On the other hand, Melanoides tuberculata is not a host for other parasites – for example, the causative agents of schistosomiasis. So it has been used successfully (like another popular species, Marisa cornuarietis) to eradicate the domestic species of snails that help spread the disease. For example, in Brazil – where it has been introduced unintentionally, probably again as aquarium “waste” – it is successfully displacing the snail Biomphalaria glabrata and thus helping to combat schistosomiasis. The mechanism of this competition is not yet fully understood and the pisciform is multiplying incredibly in new areas, so caution is needed. It can survive prolonged periods of drought or unsuitable temperatures, so getting rid of it is not easy.
Melanoides tuberculata is an excellent aquarium helper. It looks after the quality of the substrate, eliminates debris and dead plant leaves and is also a reliable indicator of water quality. Aquarists complain about only one thing in its case – it can sometimes become terribly overpopulated. But this is not the fault of the pisciform; it just shows us that it finds enough food in the aquarium.