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" covers multiple species. The two most common in aquariums are Planorbella duryi (a tropical species endemic to Florida) and Planorbarius corneus (a temperate European species); both belong to the family Planorbidae. The Columbia ramshorn (Marisa cornuarietis) is a different family entirely, Ampullariidae. P. duryi does not tolerate consistently high temperatures well in some reports, while P. corneus does not like consistently warm water. Shell is flat and planispiral, coiling in a single plane to give the characteristic ram's horn shape; typical adult shell diameter is 15-25 mm. Shell color varies from brown and reddish to blue morphs, influenced by genetic factors and environment; multiple color forms have been selectively bred for the trade. Simultaneous hermaphrodites: each individual has both male and female reproductive organs, and isolated snails can self-fertilize. Eggs are laid in gelatinous clusters on submerged surfaces; each clutch contains roughly 12-40 eggs, hatching in 7-14 days depending on temperature. Lung-breathers with a vascularized mantle cavity functioning as a lung, enabling atmospheric air breathing and survival in low-oxygen water. Population in aquariums is largely controlled by food availability; in tanks free of excess detritus, they rarely become a nuisance. Members of the family Planorbidae can serve as intermediate hosts for trematode parasites of medical importance.

Breeding

Hermaphroditic. Each individual has both male and female reproductive organs and any two ramshorns can mate. After mating, either individual can lay eggs. Egg clutches are transparent, gelatinous discs containing 10-40 eggs, deposited on hard surfaces (glass, plant leaves, decor). Eggs hatch in 10-14 days at 22–26°C. Juveniles are immediately self-sufficient, grazing on biofilm and algae. Reproduction is continuous and tracks food availability. In overfed tanks, populations boom. In clean, lightly fed tanks, populations stay moderate. A single snail can found a colony because individuals can self-fertilize if no mate is available, though cross-fertilization between two individuals is more common. Selective breeding for color morphs (red, blue, pink) requires separating lines and culling undesired colors over generations.

Common problems

Population explosions are the main concern. In overfed tanks, ramshorns reproduce rapidly and cover every surface. Control: reduce feeding, introduce assassin snails, or manually remove excess snails. Chemical treatment (copper) kills all invertebrates and is a last resort. Shell erosion in soft, acidic water (pH below 6.5, low GH) weakens and dissolves the shell. Ramshorns need calcium for shell health; maintain GH above 6 and consider adding a calcium source (cuttlebone, crushed coral in the filter). Pitted or eroded shells indicate mineral deficiency. The accusation that ramshorns destroy planted tanks is overstated: in well-fed setups, they preferentially eat algae and decaying matter. Plant damage occurs mainly when they're underfed.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size