Marisa cornuarietis

17. January 2025

Marisa cornuarietis, originally from Colombia, is one of the largest freshwater snails kept in the aquarium. Its disk-shaped shell can reach over 5 cm in diameter. This is why the species has been continuously kept in aquariums since the 1930s, although it is only suitable for special aquariums without plants. Sooner or later every aquatic plant will fall victim to it. Because of its long antennae, Marisa should not be kept with curious fish, as they are all too easily tempted to nibble at the antennae. Marisa sooner or later acknowledges this by hardly getting out of the house and slowly starving to death.

Marisa cornuarietis used to often be offered under the name Marisa rotula, but this name is now only used as a synonym for M. cornuarietis. Only a second, externally very similar species is currently recognized in the genus Marisa: M. planogyra from the Pantanal. It remains somewhat smaller than M. cornuarietis. To our knowledge, it has not yet been (recognized) kept in the aquarium.

Systematically, Marisa belongs to the apple snails. In fact, newly hatched juveniles do not yet have the typical disc-shaped Marisa shell, but look very similar to “normal” apple snails. However, this will change as they grow up. In contrast to true apple snails of the genus Pomacea, Marisa lay their eggs under water. Pomacea are known to spawn outside the water. But just like Pomacea, Marisa must regularly come up for air at the surface of the water with a “snorkel”, otherwise it will drown.

Because Marisa also eats small snails and is so efficient at cleaning up aquatic plants, it was often released as a biological beneficial organism in many parts of the world until the turn of the millennium. However, it has been shown that in all these cases the undesirable side effects outweighed the hoped-for success. The species is now considered invasive and undesirable. There are two occurrences in Europe: one in Spain and one in a thermal stream in Hungary. In both cases, irresponsible people have released these animals. This has brought the snails to the attention of the relevant authorities. Calculations from climate models show that these tropical children could theoretically survive in many parts of Europe around the year 2070. To prevent this, they are considering banning the cultivation and breeding of Marisa cornuarietis throughout Europe. This shows once again what trouble a few misguided people can cause, from which a large majority of responsible contemporaries then have to suffer. So: please never release any animals or plants into the wild. Not only is this forbidden, it is also to the detriment of all.

For our customers: the animals have code 485313 on our stock list. Please note that we only supply the wholesale trade.

Text & photos: Frank Schäfer