Aquarium Snail Tank Mates and Compatibility

What makes a good tank mate for aquarium snails?

A good snail tank mate does not eat or pick at snails, shares hard, alkaline water and never needs copper-based treatment. The three snails in our fact base are the nerite snail (Neritina natalensis (now Vittina natalensis); hobby name covers several Neritina and related nerites), the mystery snail (Pomacea diffusa) and the assassin snail (Anentome helena). Their published needs give four criteria.

1. Not a snail eater. Aquarium Co-Op and Maidenhead Aquatics list pufferfish, snail-eating loaches and large or aggressive cichlids as threats to nerites and mystery snails, and the assassin snail itself eats other snails.
2. Not an antenna-nipper. Aquarium Co-Op says bettas may mistake a mystery snail’s long antennae for worms, and the nerite’s sources list fish that nip antennae among its threats.
3. Shared alkaline water. All three snails need alkaline water: the nerite at pH 7.2–8.0, the mystery snail at pH 7.2–8.0 and the assassin at pH 7.2–8.0. Soft-water fish with a lower pH ceiling share no range with them.
4. A copper-free tank. Maidenhead and Shrimp and Snail Breeder say nerites do not tolerate copper medications, and Aquarium Co-Op calls mystery snails very sensitive to copper, including copper in tap water.

The table below sets the three snails side by side. For other species groups, the tank mates by species index lists every hub.

Which aquarium snails are best for a community tank?

The nerite snail is the safest all-round choice, the mystery snail suits owners who accept breeding, and the assassin snail is a specialist for pest-snail control. Each fills a different role.

Nerite snail: the algae grazer that cannot overrun a tank

Nerites graze algal film on glass and hardscape, and Practical Fishkeeping notes that algal film is most of what they eat in the wild. Their eggs do not hatch in freshwater: Shrimp and Snail Breeder says the capsules need brackish water and Maidenhead says hatching needs marine conditions, so a nerite population cannot grow in an aquarium. Aquarium Co-Op calls them peaceful and not particularly social, so a single nerite is fine. The nerite pairs well with nano species too, and in our data it is rated compatible with cherry shrimp. Nerites are among the grazers named on the green algae causes and fixes page.

Mystery snail: the larger scavenger

The mystery snail grows to 2.6 in (6.6 cm) and eats fish food, algae, biofilm and dead plants and animals, according to Aquarium Co-Op. Applesnail.net says it leaves healthy plants alone unless starving, though Co-Op notes it will eat duckweed and other small floating plants. It breeds easily: Applesnail.net reports clutches of 200 to 600 eggs laid above the waterline, and Co-Op says one snail per tank prevents breeding. A lid and an air gap are needed because it breathes through a siphon and climbs out of the water to lay. Surplus snails and egg clutches belong in the bin or with another keeper, not in local water: USGS (profile revised 2019) lists Pomacea diffusa, the mystery snail, as established in the wild in Florida and Hawaii.

Assassin snail: the pest-snail hunter

Assassin snails are used to control bladder, ramshorn and Malaysian trumpet snail infestations, according to Aquarium Co-Op and Shrimp and Snail Breeder. They need a male and a female to breed and lay single eggs slowly, so they do not overrun a tank themselves. Once the pest snails are gone, Shrimp and Snail Breeder says they need bloodworm, sinking carnivore pellets or similar protein or they will starve.

Which aquarium fish eat snails?

Pufferfish, snail-eating loaches and large or aggressive cichlids eat snails, according to the care sources for the nerite and mystery snail; Applesnail.net adds turtles. None of those snail specialists is in our species data, so we cannot score them, but the sources leave no doubt about the risk.

Among the species we do hold, no fish is recorded as a confirmed snail eater, but several carry a related risk. The cases are listed below, from greatest risk to least.

• Oscars: Aquarium Co-Op says an oscar eats any fish or invertebrate small enough to fit in its mouth. The nerite and oscar pairing scores 8/10 on water and temperament, but the nerite’s own sources list large cichlids among its threats, so treat that score with care. The oscar tank mates hub covers its other companions.
• African cichlids: the yellow lab, kenyi and peacock are recorded as invertebrate hunters, and Shrimp and Snail Breeder advises against keeping assassin snails with cichlids. The African cichlid compatibility matrix shows each pairing.
• Bettas: no source in our data says bettas eat snails, but Aquarium Co-Op warns they may nip mystery snail antennae and prefers other snails with them. The compatible tank mates for bettas list the nerite as the lowest-risk companion.
• Goldfish: fishkeeping.co.uk says goldfish eat anything that fits in their mouth. They also need cooler water than the nerite and assassin snail.

Several bottom dwellers are recorded as snail-safe. Aquarium Co-Op says bristlenose plecos eat only animals already dead, and it lists mystery snails alongside corydoras, tetras and kuhli loaches; the compatible tank mates for corydoras hub ranks the cory’s other options.

How do nerite, mystery and assassin snails score with common fish?

Most peaceful community fish that share alkaline water score well with all three snails, while soft-water specialists fail on pH alone. The matrix lists each pairing’s verdict and score, calculated from the same published data as the rest of the site; the how scores are calculated page explains the factors.

Can assassin snails live with nerite and mystery snails?

Not safely. Aquarium Co-Op says assassin snails attack mystery, nerite and Sulawesi rabbit snails, and Shrimp and Snail Breeder notes that several assassins may hunt larger prey together. The assassin and nerite pairing has a fit score of 8/10 on water and size and is rated caution; the assassin and mystery snail pairing is rated caution. Predation, not water, is the deciding risk, so keep an assassin only where you want snails removed.

Shrimp are a smaller risk. Aquarium Co-Op lists dwarf shrimp as safe with assassin snails, while Shrimp and Snail Breeder says they catch weak, sick or moulting shrimp and does not recommend them with expensive Caridina. Assassins also eat fish eggs and newly hatched fry, according to Co-Op, so they are a poor choice in a breeding tank.

Do aquarium snails need calcium and hard water?

Yes. Snail shells are built from the minerals in the water and diet, and the sources for both common grazers tie shell damage to soft water. Aquarium Co-Op says cracked or eroded nerite shells in soft water signal a need for more calcium and minerals, and that pits and divots in a mystery snail’s shell signal a mineral shortage. Applesnail.net warns that water for mystery snails should not be too soft, and Co-Op recommends calcium-rich vegetables and snail foods.

General hardness (GH) is the measure that tracks calcium and magnesium. The nerite is listed at 10–15 dGH and the mystery snail at 8–12 dGH; the assassin’s 6–20 dGH comes from Shrimp and Snail Breeder alone. Our guide to general and carbonate hardness explains how to test and raise GH. No source in our data gives a separate calcium figure in mg/L for any of the three snails, so GH is the number to manage.

Can snails share a nano tank with shrimp?

Yes. Nerite and mystery snails are among the best-matched companions for cherry shrimp in our data: the cherry shrimp and mystery snail pairing scores 10/10, and nerites, cherry shrimp and mystery snails all calculate at 5 US gal (19 L) together. Shrimp and Snail Breeder says nerites compete with other snails only for food and do not bother shrimp. The best cherry shrimp companions hub ranks the rest of that list.

In a small community tank with fish, the shared figure rises to the fish’s own minimum. For a full stocking example, see the guide to choosing fish for a 10-gallon community tank, and use the stocking calculator to check whether a planned list fits. Crystal red shrimp are the exception: they need softer, more acidic water than any of the three snails, and share no pH range with the nerite.

When does keeping snails with fish go wrong?

Snail tanks fail most often through medication, soft water or escape, not through tank mates. The main failure points are listed below, most common first.

• Copper treatments. Nerites are intolerant of copper-based medications, and mystery snails are very sensitive to copper and to salt, according to Maidenhead, Shrimp and Snail Breeder and Aquarium Co-Op. Check any treatment label before dosing a tank that holds snails; the white spot disease guide covers which ich treatments are hard on invertebrates.
• Soft, acidic water. Kuhli loaches, chili rasboras and GloFish tetras share no pH range with the nerite, so those pairings fail on water alone.
• Escapes. Co-Op says nerites crawl out of open tanks, and both nerites and mystery snails need a tight-fitting lid.
• Starvation. An assassin snail with no pest snails left needs added protein, and Practical Fishkeeping notes that nerites rely on algal film.

To test a specific pairing against the same data, use the species compatibility checker.

Will nerite snails overrun an aquarium?

No. Nerites lay eggs in freshwater, but the eggs need brackish or marine water to hatch, and Aquarium Co-Op notes that any larvae hatched in freshwater do not survive. The white egg capsules are the part that lasts: Practical Fishkeeping says the hard capsules on wood and rock are difficult to remove. Mystery snails are the opposite case; they breed readily in freshwater, so keeping one snail is the simplest control. Kuhli loaches are a related misconception. They are loaches, but Aquarium Co-Op says they are not known for eating snails, unlike the snail-eating loaches the sources warn about.