The snail your local fish store sells as an "apple snail" is almost certainly the same animal sold a town over as a "mystery snail." Pet shops use the names interchangeably, which only matters because there is a separate species also called "apple snail" that's banned in much of the US and will eat every plant in your tank.

This guide covers what you actually have, what they need, who to house them with, and why they so often die in their first month.

What "apple snail" actually means

Four snails get sold under the apple snail / mystery snail umbrella. Knowing which one is in your tank decides almost every care choice you make.

• Pomacea diffusa is the hobby snail. Sold as both "spike-topped apple snail" and "mystery snail." Stays around 1.5–2 inches. Comes in gold, blue, ivory, jade, magenta, and wild-type brown. Plant-safe in almost all cases.
• Pomacea bridgesii gets used interchangeably with P. diffusa in the US trade. In strict taxonomy these are now separate species, but the snail you'll see in shops is almost always P. diffusa regardless of the label.
• Pomacea canaliculata is the "channeled apple snail" or "golden apple snail." Grows to 3+ inches, eats live plants aggressively, and is one of the world's worst invasive species. Federally banned in the US since 2006, illegal in the EU. If you're outside those regions, avoid anyway unless you actively want a plant shredder.
• Asolene spixi is the "spixi" or "zebra apple snail." Smaller, eats pest snails. Different genus, similar care. Worth a mention because it shows up in the same shop tanks.

For the rest of this guide, when I say "apple snail" I mean Pomacea diffusa. If you have something else, the food and tankmate sections still mostly apply; the plant section does not.

Tank and water

• Tank size: 5 gallons minimum for one, 10 gallons for two or three. Like most snails, they're not active enough to need a lot of swimming room, but they produce real waste and benefit from the water stability a larger tank gives you.
• Temperature: 68–82°F. Room temperature is fine. They slow down below 65°F and stop eating around 60°F.
• pH: 7.0–8.0. They do not tolerate acidic water for long.
• Hardness: moderate to hard. This is the parameter most people miss. Apple snails build their shells out of calcium carbonate; soft, acidic water dissolves the shell faster than they can replace it. If your GH is below 6, supplement with crushed coral in the filter, a cuttlebone, or Seachem Equilibrium. A pitted, white-edged shell means your water doesn't have enough calcium and the snail is in trouble.
• Lid: required. They climb out. They will sit on the rim, retract, and fall to the floor where they'll die of dehydration in a few hours. Cover any HOB filter cutouts with sponge or mesh.

What they eat

Apple snails are omnivores that lean herbivore. They'll graze on algae, but you cannot keep a healthy adult snail alive on a clean tank's algae alone. You have to feed them.

• Sinking pellets or wafers. Algae wafers, Hikari Crab Cuisine, shrimp pellets, Repashy Soilent Green. One wafer per snail every few days is plenty.
• Blanched vegetables. Zucchini, cucumber, spinach, kale, broccoli stems. Drop in a slice for a day, remove what's left. They love this.
• Calcium supplements. A cuttlebone (the kind sold for parrots) floating in the tank is the easiest option. They'll rasp at it as needed.

What they will eat that you didn't want them to: any fish food that falls to the floor, dead fish, dead shrimp, and biofilm. This is a feature, not a bug. They keep the substrate clean.

What they generally won't eat: healthy live plants. They will eat dying or rotting plant matter, which is sometimes mistaken for them killing the plant. If you have an apple snail and your sword leaves are vanishing, the plant was probably dying first and the snail was just cleaning up. The clear exception is Pomacea canaliculata, which absolutely will eat your live plants.

Tankmates that work and ones that don't

Work: small, peaceful community fish. Tetras, rasboras, corydoras, otocinclus, honey gouramis, peaceful livebearers. The snail keeps to itself and the fish ignore it.

Skip:

• Loaches of almost any kind. Yoyo, clown, zebra, kuhli will all pick at snails, and the bigger species will eat them. Zebra and kuhli loaches are usually fine because they're too small to do serious damage, but assume "loach in the tank" means "no apple snail."
• Pufferfish. Any of them. Snails are puffer food.
• Goldfish larger than the snail. They'll bite the antennae and eventually crack the shell.
• Cichlids big enough to flip them. Convict, oscar, anything that rearranges substrate. They might not eat the snail but they'll harass it constantly.
• Crayfish. They will catch and eat snails, especially at night when the snail is moving.
• Assassin snails. Sold specifically to kill snails. Will go after the smaller offspring.

Shrimp (cherries, amanos) are fine and ignore each other.

Breeding and population control

Apple snails are gonochoristic, meaning you need a male and a female. Get only one and you'll never have a population problem. Get two or more and you should plan for offspring within a couple of months.

The breeding pattern is unusual: females climb above the water line and lay a pink-orange clutch of 100+ eggs on glass, the lid, or hardscape. The clutch is not submerged. Hatching takes 2–4 weeks.

To control population without killing eggs, two options work:

1. Remove clutches before they hatch. Scrape them off with a razor blade or fingernail into the trash. The clutches are dry; this isn't gross.
2. Lower the water level by an inch. Then knock new clutches into the water as soon as you see them. Submerged clutches don't develop.

A 10-gallon tank with a breeding pair can produce 1,000+ baby snails in a year if you let them run. They'll outpace the tank's bioload and crash everything. Be deliberate about this from the start.

Why yours keeps dying

The five most common causes, in order:

1. Soft, acidic water. Their shell dissolves. Test your GH and KH; supplement calcium if low.
2. Not being fed. People assume snails live on algae. Adult apple snails don't. Feed them every 2–3 days.
3. Inactivity mistaken for death. Healthy snails sit motionless for days, especially right after a water change or temperature shift. The "smell test" is the only reliable check. A dead snail smells terrible within hours. A snail that looks dead but has no smell is just dormant.
4. Climbing out. No lid, or a lid with gaps near filter cutouts. The snail falls behind the tank and dries out.
5. Wrong tankmates. See above.

Apple snails are short-lived even when everything goes right. 1–2 years is normal. A snail that lives past 2 years is doing better than average. If yours dies after 18 months and the shell looked good, that's a successful run, not a failure.

Picking your snail at the store

Look for an animal that's actively moving, gliding along the glass with its foot visible. Check the shell: it should be smooth and intact, no white pitting at the leading edge. A heavily pitted shell means the snail was kept in soft water before you got it, and the damage doesn't reverse. The snail can survive in good water, but the shell stays scarred.

If you're choosing between two healthy-looking snails and want to maximize odds of a pair, get one larger and one smaller. Females tend to be larger at maturity. There's no foolproof way to sex them in a store tank.

Next step

If you're still building the rest of the stocking around your snail, the Tank Builder will flag tankmate conflicts in real time. Drop the snail in, add the fish you're considering, and any compatibility issues (loaches, puffers, cichlids that flip substrate) surface immediately.