Marisa cornurieties and planorbidae ramshorn snails
By: Debra


These steps were compiled from forum posts and excerpts from Badman’s Tropical fish website and put together in this form by Debra. Thank you!

The term ramshorn snail is used to describe several different types of snails. *This contributes to aquarist becoming confused when finding that by accident they have ramshorn snails in their aquariums, or after purchase when they research their new aquatic pets.

Marisa Cornurieties – Giant Colombian Ramshorn

Operculum present, shell size often over 3cm, often with longitudinal stripes (following the whorls – spiral bands)
Marisa (Ampullariidae)

A very common ramshorn snail: Marisa snails are usually purposely purchased as an aquatic pet, and one rarely would have them in their aquariums by accident. Marisa information on many sites simply refers to them as ramshorn snails. *The information regarding them is not the same as the small ramshorn snails (Planorbidae) that arrive in our aquariums on plants and in general by accident.

Unlike other ramshorn snails , Marisa’s are not asexual. You must have a male and a female so that they can breed and lay fertilized eggs. Marisa’s are often referred to as “pet snails” not pest snails.

Marisa cornuarietis, which is often sold at pet stores under the name Columbian Ramshorn or Giant Ramshorn snail. This species is actually a type of apple snail. It is distinguished by having two pairs of tentacles, an operculum, and a siphon on the left side. Its shell is yellowish, with brown stripes running the length of the shell. These apple snails lay gelatinous masses of eggs on submerged portions of plants. They generally will not become a pest, although they can consume large amounts of plant matter.


PLANORBIDAE – The small ramshorn snail. Considered by many to be a pest snail.

No operculum, shell size less then 3cm, no stripes and/or color patterns. –> Planorbidae

Ramshorn Snails are in fact hermaphrodites. (Planorbidae species) They do posses both male and female organs. But they cannot fertilize themselves. It takes two snails, even though they are hermaphrodites. Two snails can and will fertilize each other. <That is an important fact that needs to be remembered for those of us who now have them in our aquariums. Two ramshorn snails can fertilize each other and both will lay fertilized eggs.

Most ramshorn snails are considered minor aquarium pests. They may arrive in a tank as egg bundles hidden in newly acquired plants. Although their color may make them somewhat interesting aquarium subjects, their hermaphroditic ability to breed prolifically from any two specimens can make them troublesome

One ramshorn snail kept singly can’t reproduce. It is impossible.

*There is no scientific data available that informs on whether ramshorn snails have the ability to store sperm.

Reference information: A hermaphrodite is an organism that possesses both male and female sex organs during its life. In many species, hermaphroditism is a common part of the life-cycle, particularly in some asexual animals and some plants. Generally, hermaphroditism occurs in the invertebrates,

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