Mystery Snail Care: Size, Colors, and How to Keep Them in a River Tank

Mystery snails are the golden retrievers of the snail world: big, colorful, harmless and always out where you can see them. They're also one of the best snails for a riparium, because they need an open space above the water to breed.

What they are

The mystery snail sold in most U.S. stores is Pomacea diffusa, the spike-topped apple snail. They grow to about 2 inches across and usually live a year or two. They come in gold, ivory, blue, purple, black and brown, all the same species.

They're a different animal from the larger apple snails, like Pomacea canaliculata, that are banned from interstate shipping because they destroy crops and native plants. Even so, a few states restrict apple snails in general, so check your state's rules before you buy.

Tank setup

• 5 gallons or more for one or two, more for a group.
• A lid with an air gap. Mystery snails climb out, and females climb up to lay eggs just above the waterline.
• Temperature in the mid-60s to high 70s °F. Warmer speeds them up and shortens their lives.
• Hard-ish water with some calcium. Soft, acidic water dissolves their shells.
• No copper. It's in many fish medications and kills snails.

In a river tank

Mystery snails are not strong-current animals. They'll hold on in moderate flow, but in a fast channel they get knocked loose and tumble into the intake. Give them the slow end of the tank: the pool, the plant shelf, the calm corners. If you run a strong one-way current, see our river manifold guide and plan a still zone.

A riparium is perfect for their eggs, though. The exposed rock and plants above the water give females a place to lay.

What they eat

They graze on algae and biofilm, eat leftover fish food, and will chew on soft or dying plants. Most healthy plants are left alone. Give them algae wafers, blanched zucchini or spinach, and a calcium source like a cuttlebone or a calcium-rich snail food.

The egg clutches

Mystery snails have separate males and females. A female lays a pinkish, chalky clutch of a few hundred eggs on the glass or lid above the water. The eggs hatch in two to four weeks if they stay humid.

• Want babies? Leave it alone and keep the lid on to hold humidity.
• Don't want babies? Gently peel the clutch off and freeze it before throwing it out. Never dump snails or eggs into a pond or stream.

Is it dead?

A mystery snail that's closed up and lying still may just be resting. Before you take it out, sniff it. A dead snail smells unmistakably awful, and it should come out fast before it fouls the water.

Tankmates

Peaceful fish and shrimp are fine. Avoid loaches, pufferfish, crayfish and big cichlids, which pick at their tentacles or eat them outright. Our assassin snail guide explains why assassins and mystery snails are usually OK together: the mystery snail is too big. For a smaller algae eater that doesn't breed in fresh water, see nerite snails.

Sources (3)

Wikipedia: Pomacea diffusa · Apple Snail (applesnail.net) · U.S. Fish and Wildlife Service: Spike-topped Applesnail Risk Screening (PDF)

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