Aquarium 19L+ / 5gal+ per snail (heavy bioload — bigger is safer), lidded, copper-free
Social needs
Happy alone or in groups
Diet
Omnivore grazer; needs feeding, not just algae
Time
Low
Cost
Low
Overview
The mystery snail is a golf-ball-sized apple snail bred in gold, blue, ivory, purple, and magenta, and it is far more animal than most people expect from a snail.
It cruises the glass on a broad foot, sweeps the water with long swaying tentacles, and extends a snorkel-like siphon to the surface to breathe air.
Most animals sold under the old name Pomacea bridgesii are now classed as Pomacea diffusa, but the care is identical.
It is a genuine beginner invertebrate, with two caveats that catch new keepers.
It must actually be fed, because unlike a nerite it cannot live on tank algae alone.
It also needs hard, calcium-rich, copper-free water, or its shell slowly dissolves.
Unlike pest bladder and ramshorn snails, mystery snails have separate sexes and lay their eggs above the waterline, so a single snail can never overrun a tank.
Unlike its invasive relative the channeled apple snail, a fed mystery snail leaves healthy plants alone.
Housing
Allow at least 19 litres (5 gallons) of cycled, mature water per snail, so one snail suits a 19-litre tank and a pair belongs in 38 litres (10 gallons) or more.
These snails carry a surprisingly heavy bioload for their size, so err larger and run real filtration rather than crowding them.
A tight-fitting lid is not optional, because they climb above the waterline and a snail that escapes overnight dries out and dies.
Leave a 2-5cm air gap under the lid, since they surface to breathe and females lay eggs in that gap.
Keep the water at 20-26C (68-78F), with the cooler end of that range noticeably lengthening lifespan by slowing the metabolism.
Aim for pH 7.0-8.0 and moderately hard water of GH 8 or above (roughly 150ppm and up), and keep some carbonate hardness (KH) to hold the pH steady, because soft acidic water permanently etches and pits the shell.
They are as sensitive to ammonia and nitrite as any fish, so never add one to an uncycled tank.
Any copper in the water is lethal, so check medications and some plant fertilisers before dosing.
Expect them to occasionally let go of the glass and free-fall to the substrate, which looks alarming and is completely normal.
Diet
This is a scavenging omnivore, not a self-sufficient algae eater, and slow starvation of snails expected to clean the tank is the most common way keepers get it wrong.
Feed sinking algae wafers, invertebrate pellets, and blanched vegetables such as zucchini, spinach, and green beans several times a week.
It will also tidy up biofilm, soft film algae, and any fish food that reaches the bottom.
Calcium is a dietary requirement, because the shell is built from it.
Offer cuttlebone, calcium-enriched snail foods, or homemade calcium-rich snail jello alongside hard water.
Smooth, solid new growth at the shell lip shows the diet and water are right.
Remove uncooked vegetable leftovers within 24 hours before they foul the water.
A well-fed mystery snail ignores live plants, while a hungry one may start rasping the softest leaves.
Health
The shell is the health report.
Pits, erosion, and thin white patches mean the water is too soft or the diet lacks calcium, and existing damage never repairs, it can only be stopped.
A healthy snail also pulls fully into its shell and seals the operculum, its trapdoor, snugly shut.
A snail hanging limply out of its shell and unresponsive to touch is in serious trouble.
Copper is the great snail killer, so read the label of every medication before treating a tank that houses one.
Floating at the surface is usually just trapped air in the lung and resolves on its own.
Before discarding a motionless snail, smell it, because a dead snail smells unmistakably foul within hours while a dormant one, which can stay closed for a day or two, smells of nothing.
Be honest about the timescale, since 1-2 years is a full life for this species, warm tropical tanks push it toward the short end, and only a cool tank tends to reach three.
Females lay pink egg clutches above the waterline, and unwanted clutches should be removed and frozen within a day or two, before 50-200 hatchlings arrive.
Never release snails or eggs into local waterways, because apple snails are serious invasives and release is illegal.
Temperament
Completely peaceful and unexpectedly engaging, a mystery snail patrols every surface of the tank, snorkels at the waterline, and drops off the glass to parachute down to food.
Many keepers find theirs learns feeding time and heads for the usual spot.
It suits calm community fish such as tetras, rasboras, corydoras, and livebearers.
Avoid tankmates that pick at its tentacles or eat snails outright, including tiger barbs, some bettas, loaches, puffers, assassin snails, and large cichlids.
A constantly harassed snail stays sealed in its shell and quietly starves.
It is equally content alone or in a group, provided each snail has its 19 litres (5 gallons) of water.
Keep in mind that any mixed-sex group will produce egg clutches, and a lone female can lay fertile eggs for months from stored sperm.
A good fit for
Beginners wanting a first aquarium invertebrate
Peaceful community tanks needing a scavenger
Planted tanks — fed snails leave plants alone
Keepers who want snails without a pest explosion
Anyone who wants a watchable, interactive snail
Common mistakes to avoid
Copper in medications and fertilisers — lethal
Soft, acidic, low-KH water pits the shell permanently
Starves if expected to live on algae alone
Escapes without a tight lid over an air gap
Pink egg clutches above the waterline — act within days
Beginner
Beginner
Beginner
Beginner
Beginner
Beginner