Ramshorn snail

Quick facts

Adult size

2 cm

Lifespan

can live up to 2 years

Tank zone

all

Temperament

peaceful

Difficulty

beginner

Water parameters

Temperature

18–28°C

pH

7.0 to 8.5

Hardness

5 to 25 dGH

Tank requirements

Minimum volume

10 L

Minimum length

20 cm

Flow

low

Lighting

any

Substrate

any

Feeding

Diet: omnivore, feeds primarily at the all.

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.

Vegetable matter required (algae wafers, blanched zucchini, spinach).

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.

Habitat

The common name 'ramshorn snail' covers several species in the family Planorbidae, primarily Planorbella duryi and Planorbarius corneus in the aquarium hobby. Native to freshwater habitats across the Americas (P. duryi) and Europe (P. corneus). Found in ponds, ditches, slow streams, and lake margins with vegetation. The shell is flat and disc-shaped, coiled in a plane (unlike the conical shell of MTS or the rounded shell of mystery snails). Shell diameter reaches 2–3 cm depending on species. Ramshorns have hemoglobin-based blood (red blood, unlike the copper-based blue blood of most snails), which makes the red color morph particularly vivid: the red body color shows through the translucent shell. They breathe air using a pulmonary cavity, regularly climbing to the surface to refresh their air supply. This air-breathing ability lets them survive in low-oxygen conditions. Ramshorns are ubiquitous hitchhikers in the aquarium hobby, arriving on live plants, driftwood, and substrate. Many keepers acquire them without intending to.

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

Bioload coefficient: 0.1 (very small snail; floor-lifted to validator minimum).

Bioload coefficients are calibrated against the neon tetra as the anchor (1.0). See the methodology page for the formula and how each value was derived.

Further reading

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