Mystery snail

Quick facts

Adult size

5 cm

Lifespan

can live up to 3 years; captive average 1-2 years; some make it to 3

Tank zone

all

Temperament

peaceful

Difficulty

beginner

Water parameters

Temperature

22–28°C

pH

7.0 to 8.5

Hardness

8 to 25 dGH

Tank requirements

Minimum volume

40 L

Minimum length

45 cm

Flow

low

Lighting

moderate

Substrate

any

Feeding

Diet: omnivore, feeds primarily at the all.

Algae, biofilm, and decaying plant matter are the primary natural diet. Supplement with blanched vegetables (zucchini, spinach, kale), algae wafers, calcium-rich foods (cuttlebone, snello), and sinking fish food. Mystery snails are not effective algae cleaners compared to nerites; they prefer softer surfaces and biofilm. Calcium intake is critical for shell health. A piece of cuttlebone in the tank dissolves slowly and provides a continuous calcium source. They eat constantly and produce a lot of waste relative to their size.

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

Compatibility

• Safe with all community fish that don't specifically eat snails. The operculum (trapdoor) protects them from nibbling fish.
• Assassin snails will kill mystery snails. Do not house together.
• Loaches (clown loach, yoyo loach) and puffers are snail predators. Some cichlids will also pick at snails.
• Safe with shrimp. Mystery snails are too slow to catch anything and don't eat live animal matter.
• Will not eat healthy live plants. May eat dying or melting leaves, which is beneficial.

Habitat

Pomacea bridgesii, commonly sold as the mystery snail or spike-topped apple snail. Native to South America (Brazil, Paraguay, Bolivia). Important distinction: P. bridgesii does not eat live plants. Other Pomacea species (P. canaliculata, P. maculata) are invasive plant destroyers that are banned or restricted in many countries. The species sold in pet stores as "mystery snails" are almost always P. bridgesii. Available in gold, ivory, blue, magenta, jade, and wild-type brown. The shell grows to 5–6 cm diameter. They have a lung and a gill, so they visit the surface to breathe air, which is normal behavior. Active, visible, and personable; they are the most popular large snail in the freshwater hobby.

Breeding

Egg layer that deposits clutches above the waterline. The female climbs out of the water at night and lays a pink-white calcified egg mass on the lid, hood, or tank rim. Each clutch contains 50-200 eggs. Eggs need humid air (not submerged) and hatch in 2-4 weeks depending on temperature and humidity. Baby snails drop into the water and begin eating immediately. Breeding is easy and can quickly result in too many snails if clutches aren't removed. To prevent breeding, simply remove egg clutches before they hatch. Sexing is possible by examining the shell opening: males have a penial sheath visible under the right side of the mantle.

Common problems

Shell erosion in soft, acidic water. Mystery snail shells dissolve in water with pH below 7.0 or KH below 3. The shell thins, develops white patches, and eventually cracks. Maintain GH above 8 and KH above 4 for healthy shells. Calcium supplementation (cuttlebone) helps but doesn't fully compensate for acidic water. Deep retraction (snail stays in shell for extended periods) indicates stress or poor water quality. Check for ammonia and nitrite. Copper kills snails at concentrations safe for fish; avoid copper-based medications. Mysterious deaths are often caused by getting stuck in filter intakes; cover all intake tubes with sponge pre-filters.

Bioload

Bioload coefficient: 0.6 (5 cm snail with steady waste production; less than a fish of equivalent size because of slower metabolism and lighter feeding).

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