Ramshorn snail

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: may nibble soft.

Feeding

Algae, biofilm, decaying plant matter, uneaten fish food, and blanched vegetables (zucchini, spinach, lettuce). In tanks with good algae growth, supplemental feeding may be unnecessary. For deliberately kept ramshorns (color morphs, breeding projects), feed algae wafers, blanched vegetables, and calcium-rich food (cuttlebone, snail jello made with calcium carbonate) to support shell growth. Overfeeding the tank increases ramshorn population; reduce food to control numbers.

Compatibility

• Divided reputation, like MTS. Some keepers value ramshorns as algae grazers and cleanup crew. Others consider them pests that breed uncontrollably and eat live plants.
• Safe with all fish. The only predators are snail-eating species: assassin snails, clown loaches, yoyo loaches, and pufferfish. In tanks without predators, populations self-regulate based on food availability.
• Available in several color morphs: red, blue, pink, leopard, and wild-type brown. The colored varieties are selectively bred and maintained by hobbyists who keep them deliberately.
• Will eat soft live plants when hungry. In well-fed tanks with supplemental food, plant damage is minimal. In tanks without enough algae or supplemental food, they'll graze on plant leaves.

Origin and habitat

Ramshorn snail is a catch-all name for several flat-shelled snails in the family Planorbidae, whose shells coil in a single plane like a ram's horn. The species most often sold in the trade is Planorbella duryi, the Seminole ramshorn, a small air-breathing snail endemic to Florida, while the larger Planorbarius corneus is a temperate European species sometimes kept in cooler tanks; the so-called Columbian ramshorn, Marisa cornuarietis, is actually an apple snail in a different family. Shell colour ranges from brown and reddish wild types to selectively bred red, pink, and blue morphs, and a typical adult shell is around 15 to 25 mm across. These are pulmonate snails: rather than a gill they breathe air with a vascularised mantle cavity that works as a lung, which lets them get by in low-oxygen water. They are simultaneous hermaphrodites, each animal carrying both sets of organs, so any two can breed and an isolated snail can fertilise itself. They graze algae, biofilm, and decaying matter and leave healthy plants largely alone. One thing worth knowing beyond the tank: planorbid snails are important intermediate hosts in the wild for trematode parasites, including the schistosomes that cause human and animal disease.

Breeding

Reproduction needs only one snail, since they are hermaphroditic and can self-fertilise, though two will usually cross-fertilise. Eggs go down in clear, jelly-like discs stuck to glass, plants, and decor, each holding roughly a dozen to forty eggs, and they hatch in about one to two weeks depending on temperature. The young are self-sufficient from the start, grazing biofilm and algae. Output tracks food closely: an overfed tank produces a population boom, while a lean, clean tank keeps numbers modest. Breeding the colour morphs means keeping lines apart and culling off-colour young over generations.

Common problems

Overpopulation is the usual complaint; in an overfed tank ramshorns multiply until they coat every surface, and the controls are feeding less, adding a predator such as assassin snails or a pufferfish, or simply removing snails by hand, with copper a last resort that wipes out all invertebrates. Shells thin and erode in soft, acidic water, so the tank needs enough calcium and at least moderate hardness, with a cuttlebone or some crushed coral helping. The reputation for wrecking planted tanks is overstated: well-fed ramshorns prefer algae and dead plant matter, and noticeable plant damage usually means the snails are underfed.

Bioload

Further reading

• Medicating a tank with snails and shrimp