Freshwater Fish · Snails

Zebra Nerite Snail

Vittina natalensis

Striped algae-mower that can't overrun a tankBeginner

Lifespan: 1-2 years typical, sometimes 3-5 in hard, stable water
Size: 1 in shell
Social needs: Not social; keep roughly one per 5-10 gal of algae-growing surface
Time: Minimal beyond normal tank care
Cost: Low
Diet: Algae and biofilm grazer; often refuses substitutes

Overview

What is this animal?

The zebra nerite is a thumbnail-sized snail from the coastal rivers and estuaries of East Africa, instantly recognisable by the crisp gold-and-black stripes spiralling around its shell.
It is widely considered the best algae-eater in the freshwater hobby, rasping even the hard green spot algae off glass that Amano shrimp and most other grazers cannot touch.
It is still widely sold under its former name, Neritina natalensis.

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Its defining quirk is that it cannot reproduce in a freshwater aquarium, because its free-swimming larvae need brackish or salt water to develop, so no baby snails ever appear.
Unlike pond, bladder, or ramshorn snails, a nerite can never overrun a tank, which is exactly why aquascapers trust it.
Adults reach about 1 in and typically live one to two years, occasionally three or more in hard, stable water.

Temperament

Nerites are entirely peaceful and essentially oblivious, gliding over tankmates, shrimp, and plants without interacting with any of them.
They are not social, so a single snail is perfectly content and there is no welfare reason to keep a group.

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They combine well with the shrimp cleanup crews common in planted tanks, but keep them away from loaches, pufferfish, assassin snails, and large cichlids, all of which eat or harass snails.
Expect one cosmetic nuisance in that females cement small, hard white eggs onto wood and rock, which never produce young in freshwater and are almost impossible to scrape off.

A nerite that repeatedly climbs out of the water is telling you something, usually that the algae has run out or the water quality has slipped.

A good fit for

Mature planted tanks with algae to mow
Keepers who dread snail population explosions
Aquascapes: it never eats healthy plants
Peaceful communities alongside shrimp
Beginners with an established, hard-water tank

Common mistakes to avoid

Starving in new or spotless tanks, the top killer
Soft, acidic water pitting the shell irreversibly
Climbing out: a tight lid is essential
Stranded upside down; flip it back or it dies
Copper medications, lethal to all invertebrates
Hard white eggs cemented to hardscape

Enclosure

Minimum 5 gallons

Fine alone or with company. Not social; keep roughly one per 5-10 gal of algae-growing surface

House a zebra nerite only in a mature, cycled aquarium of at least 5 gallons that already grows visible algae.
Keep the water at 72-78°F, hard and alkaline, with a pH of 7.0-8.5 and general hardness comfortably above 6dGH (6-12dGH is ideal), because soft acidic water slowly dissolves the shell.
Stock lightly, at roughly one nerite per 5-10 gallons, or the tank simply cannot grow algae fast enough to feed them.

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A tight-fitting lid is non-negotiable, since nerites routinely climb above the waterline and will wander out of an open-topped tank overnight.
Check the tank daily for a snail stranded on its back, because a flipped nerite often cannot right itself on bare glass or sand and will die within a day or two.
As with all invertebrates, never dose copper-based medications in its tank.

Check your enclosure

Supplies

Setup

Tank and stand
Filter
Heater and thermometer
Substrate, plants and decor
Liquid test kit
Dechlorinator and starter supplies

Ongoing

Sinking algae wafers
Invertebrate or snail-specific pellets
Cuttlebone or a calcium block for aquarium use
Courgette, spinach and green beans for blanching
Veg clip or stainless skewer

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Mineral or GH supplement for hard water
Fine net or tweezers for removing leftovers

Safe substrate: Fine, smooth sand · Smooth, rounded fine gravel (not for loaches or sand-sifting cichlids; sand is better for corydoras) · Bare bottom (quarantine and grow-out only)

Work out the cost

Care routine

Daily

Check temperature and equipment
Head-count and look everyone over

Every few days

Feed, or check there is algae left to grazeevery 2 days
Top up evaporationevery 3 days

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Weekly

Check for egg clutches
Check the lid and air gap
Check the shell
Keep a calcium source in the tank
Test the water
Water change and gravel vacuum
Wipe the front glass only

Every few weeks

Trim and thin the plantsevery 2 weeks

Monthly

Check supplies and reagent dates
Replace or recharge chemical media, if you use any (skip it in a blackwater tank)
Rinse the filter media

Health review: Quarterly shell and calcium review, every 3 months

Tools

Is your enclosure big enough?Check your measurements against the recommended size What will it cost?Setup, monthly and over its whole life, itemised Is this ammonia reading dangerous?Works out the toxic part from your pH and temperature

Care in depth

Diet

Algae and biofilm grazer; often refuses substitutes

Zebra nerites are near-obligate grazers of algae and biofilm, mowing diatoms, green dust, and green spot algae off glass, rocks, and wood around the clock.
They do not eat healthy plants, which makes them one of the very few snails that are truly safe in a planted aquascape.

Starvation is the most common way keepers kill them.
A brand-new or aggressively cleaned tank has nothing for a nerite to eat, and many individuals stubbornly refuse algae wafers, blanched zucchini, and other substitutes.
Leave at least one glass pane or some hardscape unscraped, and if the tank stays spotless for weeks, move the snail to a greener one rather than hoping it adapts.

Health

Signs of good health, and the common problems

A healthy nerite grips the glass firmly, moves visibly every day, and has a smooth, unpitted shell.
Shell erosion, seen as white pitting or a worn spire, signals water that is too soft or acidic; the existing damage never repairs, but harder, calcium-rich water stops it progressing.
Drip-acclimate new snails over an hour or more, as they are sensitive to sudden swings in temperature, pH, or hardness.

Many nerites die within weeks of purchase, usually from starvation in transit, copper exposure, or being sold as already-old wild-caught adults, so choose active snails gripping the glass and never ones lying loose on the bottom.
A snail that has sealed shut, has not moved for several days, and smells foul when lifted is dead, not resting.
Remove a dead snail promptly, because a decomposing nerite can foul a small tank overnight.

Is this urgent?

6 warning signs and how fast to act, 3 of them right away

In a snail tank the patient is usually the water, and the shell is the long-term health record. Test before you treat: many fish medications harm snails.

Go now

Any detectable ammonia or nitrite in a stocked tankChange 25-30% now with dechlorinated water matched for temperature and hardness, and repeat in steps through the day rather than making one large change. Stop feeding, and look for a dead snail. Test again in 12 hours. Both are directly toxic. How toxic the ammonia reading is depends on pH and temperature, so the same number can be harmless or lethal. A dead snail decomposing out of sight is a common cause in a small tank.

Now

Several snails leaving the water at oncePut them back, close the lid, increase surface movement and test the water now. One snail at the surface or above the waterline is normal: mystery snails breathe air at the surface and climb out to lay eggs, and nerites wander. Several leaving together usually means something in the water is wrong.

Now

Sudden deaths, more than one animal in a dayTake out the dead snails first, then test ammonia, nitrite, nitrate, GH, KH and temperature before doing anything else, and think back over anything new that went in. Do not add medication. Multiple simultaneous deaths usually point at the water, the equipment or something added to the tank rather than a pathogen, so rule those out first. A dead snail fouls the water quickly, which can take others with it.

Now

Today

White spots, white fuzz or white threads on the snailSnails do not get white spot (ich), so identify what you are seeing before you treat anything. If fish in the same tank have white spot, treat the fish in a separate hospital tank: copper kills invertebrates at ordinary doses, and malachite-green and formalin remedies can harm them too. White spot cannot keep going in a tank with no fish, because the parasite cannot survive without a fish host. White fuzz on a snail that has stopped moving often means it has died, so check it by smell.

Today

Soon

Sealed in the shell, or not moving, for more than two daysLift it out and smell it. A live snail smells of nothing; a dead one smells strongly and must come out now, because it fouls the water fast. If it is alive, test the water and review recent changes. Snails rest for a day or more at a time, but a long retreat into the shell is usually the earliest visible sign of a parameter drifting.

A few days

Shell pitting, thin white patches or an eroding spireTest GH, KH and pH, raise the hardness slowly if it is low, and add a calcium source. Soft or acidic water and a diet short of calcium dissolve the shell. The damage can be stopped but never repaired.

A few days

Never add new animals to a tank that is not fully cycled, and never treat blind. Read every medication, algaecide and plant treatment for copper before it goes in.

This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it, and the time to find one is before you need one.

Bedding and substrate

3 safe, 4 with a caveat, 2 to avoid

Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.

Safe

Fine, smooth sandCorrect for corydoras, kuhli loaches, eartheaters such as rams and acaras, and anything else that sifts or burrows. Barbels wear away on sharp gravel.

safe

Smooth, rounded fine gravel (not for loaches or sand-sifting cichlids; sand is better for corydoras)Rinse thoroughly before use. Grain size should be too large to swallow and too small to trap food. Kuhli loaches need sand to burrow into and rams and acaras sift mouthfuls of it; bronze and panda corydoras manage on smooth fine gravel, but sterbai corydoras need sand.

safe

Bare bottom (quarantine and grow-out only)Legitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration, and it is no long-term home for burrowing loaches or sand-sifters.

safe

With a caveat

Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.

with a caveat

Aquasoil for planted tanksExcellent for plants, but most active soils soften the water and pull pH and KH down for months, and many leach ammonia for the first weeks. Right for soft-water species; wrong for hard-water animals (livebearers, rainbowfish, goldfish, and snails, whose shells erode in soft, acidic water) unless you test GH and KH and remineralise. Cycle around it; do not stock into it.

with a caveat

Very deep sand bedsAnaerobic pockets form below about 2 inches in still sand. Either keep it shallow or keep it stirred.

with a caveat

Painted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.

with a caveat

Never

Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.

never

Anything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.

never

This is our general list for freshwater fish. We have not built one specific to Snails yet.

Top resources for more info

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