Marisa Cornurieties – Giant Colombian Ramshorn

Congratulations! You are now the proud owner of a lovely Marisa. This sheet contains the basics you should know in order to keep your new pet healthy and happy.


Marisa generally mature at approximately 2 inches in diameter and are characterized by a ramshorn shape, breathing siphon, 2 sets of tentacles (1 located by the mouth and one near the eyes) and an operculum (trapdoor).

Giant Ramshorn Snail © Susan Mast They are either brown, gold or striped chestnut/gold in color.

Unlike other ramshorns, Marisa are NOT asexual. You must have a male and a female to reproduce them. If water conditions are optimal and food supply is adequate, they may mate and lay aquatic eggs on plants or decorations. If you do not want to raise baby snails, simply siphon the eggs out or hand pick them off. The eggs will hatch within a few weeks. Babies are very small and translucent when they’ve hatched. They can be difficult to see. They will usually remain in the gravel, scavenging food, until their shells begin the hardening process. After a week or so, you will see them gradually appearing from the gravel. In time you will see the coloration come in on the shells and they will grow like weeds. They should be fed the same diet as the adults. Take great care to either cover your filter intake with a sponge, securing it with a rubber band, or to check your filter pad regularly for any babies sucked inside. Many times the babies will be fine and just need to be placed back into the tank.


Like most aquatic pets, your snail requires de-chlorinated water. You can use any readily available de-chlorinator product from most stores as long as it does not contain any medications or metal derivatives. We use Wardley De-chlorinator.


Your tank pH level must be around 8.0. You can purchase pH testing kits at your local fish store or Wal-Mart. To improve your pH level, you can utilize one of various remedies. Add cuttlebone (from the bird section) but be sure to remove the metal clip before adding it to the water. Partially bury the cuttlebone in the gravel so it doesn’t float. Some people use crushed coral to replace the gravel. You could also try adding seashells to the tank. Just be sure none of the snails can lodge themselves inside any of them. To prevent this without fail, use “clam” type shells or shells much smaller than the snails themselves. I’ve also heard of people using reptile calcium supplements but have not used them myself.


Marisa have voracious appetites and will likely ravage planted tanks. Therefore, we suggest keeping them in non-live plant tanks or in tanks you wish to discourage plant growth in.

It will be necessary to provide food for your snails, in addition to what they scavenge from your fish. Adequate foods include: Algae Wafers, Tropical Tablets, sinking shrimp pellets and any other types of sinking food for scavengers like catfish & loaches. They also enjoy rinsed canned green beans, washed fresh romaine lettuce & washed fresh spinach (also a good calcium source).


The general rule of thumb for tank size is 2.5 gallons per snail. This, of course, depends on the adequacy of filtration & aeration. Your tank must also be totally covered. If your hood has holes, like many do, where the filter & heater hang – simply use aluminum foil shaped to securely fit the holes and poke some ventilation holes in it with a skewer. Similarly, other people have told me they use duct tape to cover the holes. Marisa (and other Apple Snails) can and do leave the water.

Good fish roommates for snails include, but are not limited to, Danios, Guppies, White Cloud Mountain Minnows, Neon Tetras, Cory Catfish, etc. All of these are non-aggressive fish that cohabitate easily with snails.

Some definite fish to avoid (in most cases) are: Oscars, most Goldfish, Cichlids, Angelfish, Puffers, Loaches, Barbs (most species) and some Bettas.

Additional Questions?

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