Quick answer: most aquarium snails graze the thin film of algae, bacteria and fine debris on the surfaces of a tank, and many also eat decaying plants and leftover food. Nerites live mainly on algae, mystery snails eat decaying plants, algae, fish food and some animal matter but leave most healthy plants alone, and ramshorns eat algae and debris. When the film runs short, add a piece of sinking algae wafer or some blanched vegetable, and take out what is left within a day or two. Keep the water hard enough for their shells too: a freshwater snail takes much of the calcium for its shell from the water, as well as from its food.
We sell land snails rather than aquarium snails, and our guide to what land snails eat covers those. Several foods on our dry goods shelf go into aquariums as well, though, and some of them suit snails. This guide covers what mystery, nerite, ramshorn and apple snails eat, which of our foods fit, how much to feed and when to take it out, calcium and water hardness, copper in fish medicines, and keeping snails with fish and shrimp.
What Aquarium Snails Eat
Every surface in an established tank, from the glass to the stones, wood and leaves, carries a thin living film of algae, bacteria and fine debris, and most aquarium snails graze it as they go. What else they eat depends on the kind of snail.
Nerite Snails
In the wild, freshwater nerites live in rivers, grazing microalgae off stones and other hard surfaces. In a tank they do the same on the glass, rocks and wood.
Whether they need feeding depends on the tank. Practical Fishkeeping's view is that nerites are unlikely to starve: even a tank that looks clean carries a thin film of microscopic algae such as diatoms, which is largely what nerites eat in the wild. It suggests allowing about 20 litres of tank for each nerite. Another care guide warns that nerites in a new or very clean tank may need extra food. Both can be true: an established tank with a few nerites usually feeds them, while a new tank, a spotless one or one with several nerites may not. In that case add a small piece of algae wafer, or some blanched lettuce or cooked spinach, and take out what is left the next day.
Mystery Snails
Mystery snails are apple snails. In the aquarium trade the name usually means Pomacea diffusa, a South American species sold in gold and other colour forms. In the wild it feeds mostly on decaying vegetation, along with the film on surfaces, and it takes animal matter too: one study recorded it eating dead animals, live worms and the eggs of other snails. In feeding trials it ate very little of the living water plants it was offered. That makes it a good choice for a planted tank.
At home a mystery snail grazes the film and eats algae wafers, soft or blanched vegetables and the fish food that reaches the bottom. Apple snail keepers add frozen foods such as brine shrimp to that list.
Ramshorn Snails
Ramshorns, named for their flat, coiled shells, belong to a family of freshwater snails called the Planorbidae. They feed on algae and detritus, the fine debris of decaying matter. In a tank with fish they live on what the fish leave, along with algae and dying leaves, and their numbers follow the food: overfeed the fish and the ramshorns multiply.
Larger Apple Snails
Not every apple snail is as easy on plants. The channelled apple snail (Pomacea canaliculata), the island apple snail (Pomacea maculata) and Marisa cornuarietis, another member of the apple snail family, eat living water plants readily. Apple snail keepers warn that they can strip a planted tank. In parts of Asia where they have been introduced, the first two are pests of rice. Keep them in a tank without prized plants and feed them plenty of vegetables, alongside wafers and fish food.
Algae Wafers, Flakes and Vegetables
Algae Wafers
A sinking algae wafer is the simplest way to feed snails: it goes to the bottom, where they feed, and holds together long enough for a slow eater to find it. Our Oak and Algae Wafers are aquarium wafers that snails take, along with plecos and freshwater shrimp. Each is a dense disc 17 mm across, at 38.3 per cent protein. Herring meal and soya head the ingredients, with spirulina, alfalfa and oak bark further down, so a snail fed on them gets some animal protein with the plant matter.
Start with a piece rather than a whole wafer, see what has gone by morning, and adjust the size from there. Lift out whatever is left before it starts to break down.
Fish Flakes
Snails eat flake food too, but flakes are made for fish feeding higher in the water, so in a community tank the snails get only what drifts down past the fish. If you keep plant-eating fish such as mollies and platies, our Vegetable Flakes with Spirulina are a plant-heavy flake for them, at 40 per cent protein with spirulina and spinach in the recipe, and the snails pick up what sinks. Do not add extra flake for the snails' sake: whatever they miss fouls the water.
Blanched Vegetables and Peas
Soft vegetables are the other staple, for mystery and apple snails above all. Apple snail keepers feed lettuce, cucumber, small pieces of carrot, green beans and celery, and Practical Fishkeeping suggests blanched lettuce or cooked spinach for nerites. A few points make vegetables work in a tank:
- Wash them first. Keeper guides warn that vegetables for snails should be free of insecticides and molluscicides, the chemicals sold to kill slugs and snails.
- Soften the firm ones. Carrot and other hard vegetables need blanching: drop them into boiling water until they soften, then cool them in cold water.
- Weigh down the floaters. Cucumber and courgette float, so weigh a slice down or hold it on the bottom with a vegetable clip.
- Take them out in time. Lift out what is left within a day or two, before it breaks down and fouls the water. Fresh vegetables cloud the water sooner than dry food does.
Peas are a fishkeeper's standby for plant-eating fish, and a soaked, skinned pea half is an easy vegetable to try with snails. Our freeze-dried garden peas contain nothing but garden peas: soak a few until they soften, then pinch off the skins. Our guide to what goldfish eat shows how.
How Much and How Often
There is no fixed ration for snails. Watch how much yours clear in a day and give them about that much.
- In a tank with fish, the snails already eat what the fish leave, along with algae and dying leaves, so they may need little extra. Feed them when the glass and decor have been grazed clean, and then a small piece at a time.
- In a snail-only tank, or one with a few shrimp, feed a small amount each day and adjust it to what goes.
- Wafers go in for the night and whatever is left comes out in the morning; vegetables come out within a day or two.
Snails do eat leftovers, but they are not a way to deal with them: every snail adds waste of its own, and food that nothing eats still rots. If you are unsure, feed less.
Calcium, Water Hardness and pH
A snail's shell is made of calcium carbonate, and a freshwater snail takes much of the calcium for it from the water, as well as from its food. The water matters as much for its shell as anything you feed it, so get the water right first.
Soft or acidic water is hard on shells. In one experiment, Florida apple snails kept in the softest, most acidic water grew the weakest shells, which broke under the least force. Apple snail keepers ask for hard, calcium-rich water with a pH of 6.5 to 8, and call 7 to 8 the best range for most apple snails; in acidic, calcium-poor water a snail cannot build a strong shell, and the oldest part of the shell, at the tip, is the first to wear.
UK tap water varies a great deal. In 2021 the average calcium in the tap water of 66 UK cities ranged from about 5 to 128 mg per litre: Scotland had the softest water, and in England the north-west was softest and the south-east hardest. Your water company can tell you how hard the water is at your postcode, and an aquarium test kit for general hardness (GH), carbonate hardness (KH) and pH tells you what is in the tank.
If your water is soft, keepers raise the hardness with calcium carbonate in the tank. A common method is a small mesh bag of crushed coral, sold for aquarium use, in the filter, topped up as it dissolves. It changes the water for everything in the tank, so check first that your fish, shrimp and plants suit harder water, and test as you go.
Copper and Fish Medicines
Copper in the water is toxic to snails. The University of Florida's guide to copper in fish ponds notes that it is toxic to invertebrates such as snails, and copper sulphate is the active ingredient in some fish medicines for parasites. Apple snail keepers list copper-based treatments among the medicines that can harm their snails.
To check a medicine, read its active ingredients for copper, often printed as copper sulphate or copper sulfate. A treatment that contains it usually says so on the label, and some state that it will kill snails, shrimps and other invertebrates. If your fish need a copper treatment, move the snails to a separate tank before you dose. Be just as careful with treatments sold to kill snails: killing a lot of snails at once leaves rotting bodies that foul the water.
The copper on a food label is a different matter. Fish foods list copper among their trace minerals, as our Pleco Wafers do in their mineral premix, and there it is a nutrient. Most snails carry oxygen in their blood on haemocyanin, a protein built around copper; ramshorns are the exception and use haemoglobin, as we do. Some keeper guides tell you to avoid any food with copper on the label, but the warnings on record are about copper dosed into the water, as in medicines, not the trace amount in a food's mineral list.
Overfeeding and Snail Booms
When a tank suddenly fills with small snails, food is usually behind it. Practical Fishkeeping treats a crowd of snails as a sign that the tank holds too much organic debris. They live on uneaten fish food, fish waste, algae and dying plants, so the more of that there is, the more snails the tank supports. A dead fish left unnoticed feeds them too.
Whether a snail can boom depends on how it breeds:
- Ramshorns lay small capsules of eggs, and the young hatch as tiny snails, so a well-fed tank can fill with them quickly.
- Mystery snails have separate sexes, so you need a male and a female for eggs. Females lay clutches of pale pink to reddish eggs above the waterline, often 200 to 600 at a time; lift off any you do not want.
- Nerites lay small white egg capsules on hard surfaces, but in the wild their larvae develop in salt or brackish water, so the eggs do not produce young in a freshwater tank.
To bring numbers down, cut the food first. Feed less, net out leftovers, siphon the detritus from the gravel and trim dying leaves; a water change alone leaves the solid waste behind. Then take snails out: a slice of courgette under a saucer in the evening gathers them, and you lift them off a couple of hours later. Do not crush snails against the glass, since dead snails rot and foul the water. Assassin snails (Clea helena), which eat other snails, are another way to bring numbers down.
Most aquarium snails, apple snails and nerites among them, are not native to the UK. Never put unwanted snails or their eggs into a pond, river or canal: Defra's advice on apple snails is that they should never be released into the wild. Pass spare snails on to another keeper instead.
Snails With Shrimp and Fish
Snails and shrimp share a tank well at feeding time: both graze the film on surfaces and both take algae wafers, so a piece of wafer feeds the lot. Our guide to food for shrimp tanks and bottom feeders covers the shrimp side.
With fish, two things matter. The first is the food: in a community tank the fish reach it first, so drop a piece of wafer in after they have eaten, near where the snails are. The second is the fish themselves. Snail-eating fish, dwarf pufferfish and many loaches among them, will eat small snails, and big fish with strong jaws, cichlids among them, are a threat to apple snails. Check what you keep before you add snails.
The water has to suit everything in the tank as well. Snails need water that is neither soft nor acidic for their shells, so if your fish or shrimp need soft, acidic water, the snails will struggle in it; choose tank-mates that want the same water.
Frequently Asked Questions
What do aquarium snails eat?
Mostly the film of algae, bacteria and fine debris on the surfaces of a tank, along with decaying plants and leftover food. A piece of algae wafer or some blanched vegetable makes up the difference when the film runs short.
What do mystery snails eat?
In the wild, mostly decaying plants, plus the film on surfaces and some animal matter. At home, algae wafers, fish food that reaches the bottom and soft or blanched vegetables. They leave most healthy plants alone.
Do nerite snails need to be fed?
Not always. In an established tank with a few nerites, the algae film is usually enough. In a new or very clean tank, or one with several nerites, add a small piece of algae wafer or some blanched lettuce or cooked spinach.
What do apple snails eat?
It depends on the species. Mystery snails (Pomacea diffusa) eat mostly decaying plants and leave healthy ones alone, while the larger channelled and island apple snails eat living water plants and can strip a planted tank.
What vegetables can aquarium snails eat?
Lettuce, spinach, cucumber, courgette, small pieces of carrot, green beans and celery are all used. Wash them, blanch the firm ones, weigh floating slices down and take out what is left within a day or two.
How often should you feed aquarium snails?
Watch what your snails eat in a day and give them that much each day. In a tank with fish they may need little extra; in a snail-only tank, feed a little every day.
Do aquarium snails need calcium?
Yes. A snail's shell is calcium carbonate, and much of the calcium for it comes from the water, so keep the water calcium-rich and not acidic. Apple snail keepers give a pH of 6.5 to 8, and 7 to 8 suits most apple snails.
Our other foods for fish and aquariums are collected on foods for reptiles, turtles and fish.
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