When we feed shrimp, we drop in pellets, wafers, or a piece of blanched vegetable.
But if you watch them all day, they don’t sit around waiting for pellets.
They graze. Constantly. On glass, moss, wood, leaves, sponge filters, even the heater.
That’s because a healthy shrimp tank is quietly growing its own food.
This article is about that invisible buffet – the food web in a freshwater shrimp aquarium – and how you can support it without turning the tank into a mess.
Short Answer
In a mature shrimp tank:
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Every surface grows bacteria and biofilm.
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Light and nutrients create a thin layer of algae.
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Mulm (fine brown dust) and decaying leaves feed tiny organisms.
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Those tiny organisms, algae, and biofilm become natural food for shrimp, especially shrimplets.
Our job isn’t to keep everything spotless.
Our job is to keep this food web stable and balanced, not too sterile and not overloaded.
Step 1: Surfaces, Bacteria, and the Cycle
It starts with something simple: surfaces.
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Glass, rocks, wood, sponge filters, plant leaves, substrate – all of these are real estate for bacteria.
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When a new tank is set up and the filter is running, bacteria begin to colonise.
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Some of these bacteria handle waste:
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They turn toxic ammonia → nitrite → nitrate (the nitrogen cycle).
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Others help break down leftover food, dead plant bits, and shrimp waste into smaller pieces.
This is why:
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New tanks (less than 4–6 weeks old) are often unstable.
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Mature tanks (3+ months) usually feel calmer and more predictable
Step 2: Biofilm – The Shrimp’s Favourite Food
Once bacteria settle on surfaces, they form a thin, sometimes slimy layer called biofilm.
Biofilm is:
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A mix of bacteria, fungi, algae, and tiny organisms.
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Almost invisible at first, then more obvious as a light haze on wood, rocks, leaves, glass, or sponge filters.
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What shrimp spend most of their day picking at.
You can think of it as:
“A salad bar growing directly on your hardscape.”
If you’d like the more detailed version, I have a full article on biofilm in aquariums – how it forms, why it matters.
For shrimplets (tiny baby shrimp), biofilm is critical:
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They’re too small to fight for pellets.
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They need to eat often.
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They feel safer eating in hidden places (inside moss, under leaves, on sponge filters).
Step 3: Algae – Friend, Not Enemy (in Reasonable Amounts)
Algae often gets treated as something to “defeat”.
In shrimp tanks, mild algae is a good sign:
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Green film algae on glass: shrimps and snails will graze it.
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Soft algae on wood and rocks: shrimp buffet.
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Algae on plant leaves: not pretty in photos, but useful in life.
Problems only start when:
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Algae grows too fast (often from too much light + nutrients).
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It covers plants so heavily that they can’t photosynthesise.
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It becomes hard, dark, or thick mats (e.g. black beard algae, long hair algae).
You don’t have to keep the tank spotless:
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Clean the front glass for viewing.
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Leave some algae on side glass, wood, and rocks for grazing.
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Use snails and maybe gentle algae eaters (like otocinclus in mature tanks) as support, not as a fix.
Step 4: Mulm and Detritus – The Brown Dust at the Bottom
If you look closely at a mature tank, you’ll see fine brown dust in corners, under hardscape, and in plant roots.
This is mulm – a mix of:
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Tiny bits of decaying leaves.
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Microscopic poop.
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Tiny pieces of algae.
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Bacteria and other microorganisms.
Mulm:
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Feeds bacteria and microfauna.
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Slowly releases nutrients for plants.
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Becomes part of the “soil” in deeper substrate setups.
Shrimp often pick through mulm, especially in quiet areas.
What to do with mulm:
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Don’t panic and vacuum everything shiny every week.
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Gently siphon the worst piles if they’re very thick.
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Leave a thin layer under hardscape, in plant roots, and inside moss.
If you’re running deep substrate, mulm is part of the system, not a mistake – I talk more about that in my deep substrate aquarium setup guide.
Step 5: Microfauna – Tiny Worms and Creatures
As a tank matures, you may start seeing tiny moving things:
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Little white dots hopping on glass (often copepods).
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Tiny white worms in the water column or on glass.
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Infusoria-like “dust” in the water under strong light.
Most of these microfauna are harmless, and many are useful:
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They help break down waste and leftover food.
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They become live food for shrimp and fish fry.
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Shrimplets nibble on them as part of the natural diet.
When to relax:
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They are small, scattered, and shrimp/fish are happily grazing on them.
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Water is clear, no bad smell, parameters look normal.
When to pay attention:
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Sudden explosion in population (thick clouds, swarms).
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Often a sign of overfeeding and too much organic waste.
What to do if there are too many:
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Reduce feeding slightly.
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Increase gentle maintenance (small water changes, light siphoning).
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Check filter performance and stocking levels.
Most of the time, they’re just another piece of the invisible buffet, not a crisis.
Step 6: Plants, Wood, and Leaves
Live plants, wood, and dried leaves are not just decorations. They’re food factories.
Plants
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Provide surface area for biofilm and algae.
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Take up nitrate and help keep water cleaner.
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Offer hiding spots for shrimplets.
Fine-leaved plants and mosses (like java moss, subwassertang, etc.) are especially useful because:
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Shrimplets can hide deep inside.
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Every tiny strand can hold biofilm and microfauna.
If you’re choosing plants for a shrimp tank, here’s aquarium plants: simple guide to what I actually use.
Wood and Hardscape
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Driftwood and rocks grow biofilm and algae.
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Small caves and gaps create safe grazing spots where fish can’t reach.
Leaf Litter and Humic Substances
Catappa, guava, and other botanicals:
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Break down slowly into soft material shrimp can eat.
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Grow biofilm and microfauna.
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Release humic substances and tannins that can support a more natural environment.
Where Prepared Food Fits In
If a tank grows so much natural food, do we still need pellets and wafers?
Yes – but think of them as supplements, not the whole diet.
Why we still feed:
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Natural food can fluctuate (new tanks, heavy cleaning, or seasonal changes).
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Shrimp colonies can grow faster than the tank’s natural production.
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Prepared food lets us target specific nutrients (minerals, proteins, etc.).
General pointers:
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Feed small amounts and watch how fast they disappear.
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In shrimp-only tanks, feed every 1–2 days, with at least some days lightly fed.
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In shrimp + fish tanks, remember fish are faster – consider feeding shrimp in hiding spots (inside moss, under a small overhang).
If you write a dedicated feeding article, you can later link it from here.
How to Encourage a Healthy Food Web
You don’t have to guess. Here are practical steps.
1. Let the Tank Mature
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Aim for 4–6 weeks minimum between first filling and adding a full shrimp colony.
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You can add a few hardy snails early to help start the cycle.
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Test for ammonia and nitrite until they stay at 0.
2. Use Varied Surfaces
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Combine glass, wood, rocks, and leaves.
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Use sponge filters or pre-filters – shrimp love grazing on sponges.
3. Add Plants and Moss
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Moss and fine plants increase surface area dramatically.
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Heavily planted tanks buffer nutrient swings and help with algae control.
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For plant choices and simple layouts that work with shrimp, you can read aquarium plants: simple guide to what I actually use.
4. Don’t Over-Clean
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Avoid scrubbing all glass and surfaces at once.
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Clean viewing panels and leave some algae on the sides/back.
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Rinse filter sponges in old tank water, not under the tap.
5. Feed Lightly and Observe
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Start with very small amounts of food.
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If food is still there after a couple of hours, you’re probably feeding too much.
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Watch how shrimp behave – are they constantly finding things to pick at?
6. Use Deep Substrate (Optional)
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Deep substrate setups can store more nutrients and support more bacteria and microfauna.
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deep substrate aquarium setup guide shows how I build tanks that can store more nutrients and support more bacteria and microfauna.
Signs the Food Web Is Working
How do you know your invisible buffet is doing its job?
Look for:
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Shrimp grazing calmly most of the day, not all rushing to every pellet in a panic.
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A thin film of algae or biofilm on wood, rocks, and older leaves.
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Occasional microfauna visible under strong light, but not clouds of them.
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Berried females, shrimplets of different sizes, and slow, steady colony growth.
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Water that is clear, with no rotten smell.
When Things Are Out of Balance
Too Sterile
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Glass is scrubbed constantly.
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No visible algae anywhere.
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Shrimp seem restless and rush to every bit of food.
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New tanks with strong filtration and frequent “reset-style” cleaning.
What to do:
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Clean less aggressively.
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Add more natural surfaces (wood, leaves, moss).
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Reduce water change frequency a little, but keep them regular and gentle.
Too Dirty
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Thick algae layers, cloudy water, strong smell.
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Explosions of worms or other critters.
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Shrimp hiding a lot, slow or poor breeding.
What to do:
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Reduce feeding.
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Increase small, frequent water changes (for example 10–20% a few times a week).
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Siphon excessive mulm from open areas.
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Check your filter, stocking level, and lighting duration.
Balance lives in the middle: not spotless, not swampy.
Gentle Closing Thought
It can be tempting to see the aquarium as something we completely control:
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We add food.
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We clean when we want.
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We decide every number in the water.
But shrimp live closer to the “edges” of the tank – in moss, under wood, inside leaf piles.
For them, the slow, quiet processes matter more than our neat schedule.
When you see your tank as a small ecosystem:
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Patience feels easier.
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A little algae no longer feels like failure.
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Microfauna and mulm become signs of life, not dirt.
You’re not just keeping shrimp.
You’re tending a tiny kitchen that cooks all day, every day, whether you’re watching or not.
You might also like:
- Neocaridina vs Caridina: which shrimp should I start with?
- Shrimp-safe tank mates: who can live with Neocaridina and Caridina?
- Biofilm in aquariums – how it forms, why it matters
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