Freshwater Fish · Snails
Zebra Nerite Snail
Neritina natalensis
Striped algae-mower that can't overrun a tankBeginner
- Lifespan
- 1-2 years typical, sometimes 3-5 in hard, stable water
- Size
- 2-2.5cm (about 1in) shell
- Social needs
- Not social; keep roughly one per 5-10gal 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.
- Its defining quirk is that it cannot reproduce in a freshwater aquarium, because its larvae need brackish or salt water to hatch and develop.
- Unlike pond, bladder, or ramshorn snails, a nerite can never overrun a tank, which is exactly why aquascapers trust it.
- Adults reach about 2.5cm (1in) 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.
- 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 hatch 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
- Unhatchable white eggs cemented to hardscape
Enclosure
Minimum 19 litres (5 US gallons)
Fine alone or with company. Not social; keep roughly one per 5-10gal of algae-growing surface
- House a zebra nerite only in a mature, cycled aquarium of at least 5 gallons (19L) that already grows visible algae.
- Keep the water at 72-78F (22-26C), 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.
- 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.
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
- Mineral or GH supplement for hard water
- Fine net or tweezers for removing leftovers
Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks
Care routine
Daily
- Check temperature and equipment
- Feed
- Head-count and look everyone over
Weekly
- Top up evaporationevery 3 days
- Check above the waterline for clutches
- Check the lid and air gap
- Check the shell
- Clean glass and clear algae
- Keep a calcium source in the tank
- Test the water
- Water change and gravel vacuum
Monthly
- Trim and thin the plantsevery 2 weeks
- Check supplies and reagent dates
- Rinse the filter media
Less often
- Replace chemical filter media (Carbon/Purigen)every 2 months
Vet: Quarterly shell and calcium review — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
YouTubers
Girl Talks FishCare how-tos by fish type, tank setup and beginner mistakesAquarium Co-OpSpecies care guides, filtration and fish health (run by a retailer)Prime Time AquaticsSpecies profiles, stocking and water chemistry explained plainly
Sites
Go deeper
Diet
- 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
- 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 your enclosure big enough?
Minimum volume19 litres (5 US gallons)
CompanyFine alone or with company. Not social; keep roughly one per 5-10gal of algae-growing surface
Is this urgent?
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Any detectable ammonia or nitrite in a stocked tankLarge water change now with dechlorinated, temperature-matched water. Stop feeding. 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.
NowFish gasping at the surface, or crowding the filter outflowIncrease surface agitation immediately, then test the water. Either the oxygen has crashed or the gills are being chemically burned. Both are hours-scale problems.
NowSudden deaths, more than one fish in a dayTest ammonia, nitrite, nitrate and temperature before doing anything else. Do not add medication yet. Multiple simultaneous deaths point at the water or the equipment, not at a pathogen.
NowToday
Flashing — repeatedly scraping against decor or substrateTest the water, then look closely for parasites. Irritation is either chemical or parasitic; the test tells you which before you medicate.
TodayWhite salt-grain spots over the body and finsBegin the appropriate treatment today and check the temperature. The parasite's life cycle is temperature-driven, and it multiplies with every cycle you wait.
TodaySoon
Clamped fins, hiding, or refusing food for more than two daysTest the water and review recent changes. Usually the earliest visible sign of a parameter drifting.
A few daysNever add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
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.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.
Safe
Inert aquarium gravelRinse thoroughly before use. Grain size should be too large to swallow and too small to trap food.
safeFine, smooth sandCorrect for corydoras, kuhli loaches and anything that sifts. Their barbels wear away on sharp gravel.
safeAquasoil for planted tanksExcellent for plants, but it leaches ammonia for the first weeks. Cycle around it; do not stock into it.
safeBare bottomLegitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration.
safeWith a caveat
Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.
with a caveatVery deep sand bedsAnaerobic pockets form below about 5 cm in still sand. Either keep it shallow or keep it stirred.
with a caveatPainted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.
with a caveatNever
Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.
neverAnything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.
neverThis is our general list for freshwater fish. We have not built one specific to Snails yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
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