Most planted-tank owners hunting for the best algae eaters for planted tank walk out of the fish store with the wrong animal for their actual problem. Algae is not one thing, and neither are algae eaters: the famous shrimp that demolishes hair algae will completely ignore black beard algae, and the fish that grazes green spot algae off your glass won't touch a thread-algae infestation. The right cleaner is the one matched to your specific algae type, your tank size, and your plants' safety — this guide is built around that matching process, not a generic top-10 list.
One Crucial Caveat: Algae Eaters Treat the Symptom
Before matching eater to algae, be honest about the cause. Algae in a planted tank is a signal — usually an imbalance between light, CO2, and nutrients. Algae eaters are a maintenance tool that keeps a healthy tank pristine and holds the line while you fix the underlying imbalance, not a substitute for fixing it. Pair this guide with stable water parameters for planted tanks and a regular maintenance schedule, and your cleaners will do ten times the work.
Quick-Match Table: The Best Algae Eaters for Planted Tank, by Algae Type
Use this as your starting reference, then read the sections below for stocking, compatibility, and caveats.
| Algae type | Best eater | Runner-up | Minimum tank |
|---|---|---|---|
| Black beard algae (BBA) | Siamese algae eater (true SAE) | None reliable | 20 gal |
| Hair / thread algae | Amano shrimp | Cherry shrimp (light infestations) | 10 gal |
| Brown diatoms | Otocinclus | Nerite snails | 10 gal |
| Green spot algae (GSA) | Nerite snails | None reliable | 5 gal |
| Soft green film algae | Nerite snails | Amano shrimp, otocinclus | 5 gal |
| Staghorn algae | Siamese algae eater (young ones) | Manual removal | 20 gal |
| Leftover food / detritus | Corydoras / kuhli loach | Malaysian trumpet snails | 20 gal (cory school) |
Black Beard Algae: The True Siamese Algae Eater
Black beard algae — those dark tufts clinging to slow-growing leaves like Anubias and Java fern — is the one algae type with almost exactly one reliable animal answer: the true Siamese algae eater, Crossocheilus oblongus. It is the only commonly available fish that will genuinely graze established BBA.
How to buy a real one
Three lookalike fish get mislabeled at stores. The true SAE has a black lateral stripe that runs all the way through the tail fin, with a ragged, zigzag edge. The flying fox has a crisp-edged stripe that stops at the base of the tail and is far less interested in BBA. Inspect the stripe before you buy, or ask the store to bag from a tank you can verify.
Planted-tank behavior
SAEs are among the safest fish for planted tanks: they won't uproot stems, don't eat healthy leaves, and school loosely and peacefully. The catch is motivation. Juveniles under about 3 inches are voracious algae grazers; as they mature toward 5–6 inches they increasingly prefer fish food and their BBA consumption drops sharply. Many aquascapers keep a group of young SAEs for six to twelve months, then rehome the adults. Groups of three to six are the minimum for tanks 20 gallons and up.
Hair and Thread Algae: Amano Shrimp
For the long, green filaments that tangle around moss and stem tips, nothing competes with the Amano shrimp (Caridina multidentata), the species that started the modern planted-tank cleanup movement. A working crew of Amanos will strip thread algae cleanly in days — they are the single most effective hair-algae grazer in the hobby.
Stocking and plant safety
The standard working dose is one Amano per 2–5 gallons when fighting an outbreak, settling to roughly one per 5 gallons for maintenance. They are large for shrimp (up to 2 inches), sturdy, and completely plant-safe. One quirk: in a freshly cycled tank with nothing to graze, Amanos will opportunistically nibble tender new shoots, which looks alarming but is harmless once the tank matures. For the full picture, see setting up a shrimp-focused planted tank.
When cherry shrimp are enough
Neocaridina (cherry shrimp) colonies graze algae too, just less aggressively. In a small nano tank where a 2-inch Amano feels oversized, a self-sustaining colony of a dozen cherry shrimp will handle light dustings and keep mosses clean. Cherry shrimp breed in freshwater while Amanos don't, so the colony maintains itself — but Amanos do the heavy lifting per individual. This pairing is also the answer to the classic ordering question (see FAQ): in a new planted tank, shrimp first, fish later.
Brown Diatoms: Otocinclus
The dusty brown coating that blankets new tanks in the first weeks is diatoms, not true algae — and otocinclus catfish are diatom specialists. A small school of three to six will polish leaves, glass, and hardscape in a new setup within days, working as a group the way nature designed them to.
The delicate-fish disclaimer
Otos are the cleaners most likely to die in your tank, and it's almost never your fault. They are frequently wild-caught, often arrive starved at wholesalers, and go through gut-flora changes on arrival. Buy the fattest, most active specimens, keep their bellies rounded with algae wafers or blanched zucchini from day one, and add them only to a mature, stable tank — never a fresh cycle. Once settled, healthy otos are gentle, plant-safe, and nearly invisible against the leaves they clean. Drip-acclimate them slowly; they are sensitive to sudden parameter swings.
Green Spot Algae and Film Algae: Nerite Snails
Green spot algae — the hard little green dots on glass and slow-grower leaves that resist scrapers and plecos alike — has exactly one reliable predator: the nerite snail. Species like zebra, olive, and horned nerites rasp GSA off glass overnight and are equally enthusiastic about soft film algae and diatoms. For algae control per dollar, a nerite is unmatched.
Plant safety and the egg question
Nerites are 100% plant-safe; they rasp algae off leaf surfaces without damaging tissue. The one tradeoff: female nerites lay hard, sesame-seed-like white eggs on hardscape and glass. The eggs cannot hatch in freshwater, so you'll never get baby nerites — but they are persistent and need scraping off. If the look bothers you, keep a single nerite (a lone snail still lays eggs, but far fewer). One nerite per 5–10 gallons is a solid starting dose.
Leftover Food and Detritus: Corydoras and Malaysian Trumpet Snails
Not everything labeled "cleaner" eats algae. Corydoras catfish and kuhli loaches eat uneaten food and disturb settled detritus; Malaysian trumpet snails burrow through the substrate, aerating it and eating buried debris. None remove algae from glass or leaves — but they prevent the decaying organic matter that feeds future outbreaks. A cleanup crew is a team: bottom-feeders handle waste, grazers handle algae. For how all these roles fit together, read our full cleanup crew guide.
The Two Species You Should Never Buy
The Chinese algae eater
The Chinese algae eater (Gyrinocheilus aymonieri, sold as "golden algae eater") is the pet trade's most regrettable default recommendation. Juveniles eat algae, which is why stores sell them — but adults reach 10 inches, stop eating algae, and develop a habit of latching onto slow fish to rasp their slime coats. They are territorial, aggressive, and spectacularly unsuited to planted community tanks.
The common pleco in a small tank
The common pleco (Hypostomus plecostomus) is sold at 2 inches and matures into a 2-foot bulldozer that uproots plants, produces enormous waste, and outgrows anything under 75–125 gallons. It is also a mediocre algae eater as an adult. Small planted tanks have a legitimate pleco option — bristlenose plecos (Ancistrus spp.) stay around 4–5 inches, graze glass diligently, and are generally plant-safe — but the common pleco never belongs in a 20-gallon scape.
Stocking Rules by Tank Size
Algae-eater stocking follows the algae, not the gallons — but bioload matters. Use these as starting points for an established, planted tank with a moderate algae load:
- 5–10 gallon nano: 1–2 nerite snails plus either 4–6 Amano shrimp or a colony of 10+ cherry shrimp. No SAE — too large and active.
- 20 gallon: 2–3 nerites, 6–8 Amanos, 3–4 otocinclus, and a trio of young SAEs for BBA-prone setups.
- 40+ gallon: scale the above per 10 gallons, plus a school of 6–8 otocinclus and, if appropriate, a bristlenose pleco and a small corydoras school for substrate duty.
Build the crew gradually over weeks, starting with snails and shrimp, then otos, then SAEs last. Adding everything at once to an immature tank means hungry cleaners and ammonia spikes — the same patience stocking a 10-gallon planted tank requires applies at any size.
Acclimation: The Step Everyone Skips
Shrimp and otos are the two cleaners most sensitive to water-chemistry changes, and most losses happen in the first 48 hours. Float the bag for temperature, then drip-acclimate over 45–60 minutes so the chemistry blends gradually. For Amano and cherry shrimp, sudden shifts in GH/KH are the specific killer — a shrimp that was fine at the store can die overnight in a tank with very different hardness. Nerites are tougher but still benefit from acclimation. Keep the tank lights off for the first few hours and have food available: wafers or blanched vegetables for otos, a small algae wafer for shrimp, so nobody spends its first night hunting a strange tank on an empty stomach.
Why Overfed Cleaners Stop Cleaning (and How to Feed Them Right)
Here is the paradox at the heart of algae-eater keeping: the cleaner that never goes hungry never cleans. A crew that gets flake food, algae wafers, and blanched zucchini every day will graze less — why work for algae when dinner is served? But a starving cleaner dies, and starvation is the far more common problem, especially with otocinclus.
The balance: feed enough that bellies stay rounded and animals stay active, but make algae the first course. Targeted supplemental feeding — a half wafer twice a week for otos in a clean tank, vegetables only when grazing looks thin — keeps cleaners alive without turning them into pets that wait for the hand that feeds. Shrimp in an established planted tank rarely need feeding at all; biofilm and microalgae sustain them. If your Amanos abandon the algae the day you add a wafer, you know your dosage is off.
Feed your cleaners properly with algae wafers — overfed crews stop cleaning, starved ones die: Hikari Algae Wafers.
What Eats Brown Algae: The Clean-Up Crew, Ranked Honestly
Not every famous "algae eater" eats diatoms. Some of the most-hyped species ignore brown film entirely, while unglamorous workhorses hoover it up. The honest ranking:
| Species | Diatom appetite | Min tank | Hardiness | Notes |
|---|---|---|---|---|
| Otocinclus catfish | ★★★★★ | 10 gal | Sensitive | Diatom specialists: a school strips brown film from leaves and glass within days. Fragile — need stable, mature water. |
| Nerite snails | ★★★★★ | 5 gal | Very hardy | Bulldozers for glass and hardscape. Cannot breed in freshwater. Will escape an uncovered tank. |
| Amano shrimp | ★★★★☆ | 5 gal | Hardy | Excellent on plant leaves; too small to clean large glass panels efficiently. |
| Bristlenose pleco | ★★★☆☆ | 20 gal | Very hardy | Rasps diatoms off wood and glass decently, but produces a lot of waste. Needs driftwood for digestion. |
| Malaysian trumpet snails | ★★★☆☆ | 5 gal | Very hardy | Turn substrate over while burrowing, clearing diatoms there. Breed readily — numbers track feeding. |
| Siamese algae eater | ★☆☆☆☆ | 30 gal | Hardy | The wrong tool here: it targets hair and black beard algae and ignores diatoms. Often confused with the flying fox — see our Siamese algae eater vs flying fox guide. |
The Siamese algae eater is the most overhyped diatom eater in the hobby: built for tougher filamentous algae, and at six inches it needs a 30-gallon tank.
Nerite snails ranked among the most reliable diatom grazers, ideal first buy for a new tank: zebra nerite snails.
Best pick for your setup
Nano tank (5–10 gallons). Nerite snails win — one per 5 gallons, negligible bioload, no breeding. In a cycled nano, add four or five Amano shrimp for the leaves. Skip fish grazers under 10 gallons; a stressed oto in a 5-gallon is a dead oto.
Shrimp tank. Amanos first, nerites second — both shrimp-safe and harmless to shrimplets. Avoid catfish or plecos in a breeding shrimp tank; even peaceful grazers can vacuum up a newborn shrimplet while scraping a leaf.
Big community tank (20+ gallons). Otocinclus shine here: a school of six or more suppresses diatom regrowth long-term. Add two or three nerites for the glass, and one bristlenose if you have driftwood. If hair algae is the bigger worry later, a true Siamese algae eater finally earns its keep — but buy it for that job, not diatoms.
The famous "algae eaters" that ignore it
Several animals are sold specifically as algae eaters but do almost nothing against hair algae. Knowing who to skip saves you money and stocking space.
- Otocinclus catfish. Beloved and effective — against soft brown diatoms and biofilm. Hair algae strands are too tough and long for their tiny mouths. Still worth keeping (a group of 6+ per 40 L) for brown algae, just not for this job.
- Bristlenose plecos. Excellent at green spot algae and wood grazing; they largely walk past hair algae.
- Chinese algae eater / "golden algae eater". The worst of both worlds: juveniles graze a little, adults stop eating algae entirely, grow large, and can latch onto slow tank mates. Do not buy one for hair algae — or, frankly, at all in a planted community tank.
- Black beard algae specialists. Note the reverse trap too: true Siamese algae eaters are famous black beard algae eaters, which is why people assume they handle every algae — but hair algae is a separate appetite and a separate life stage.
Stocking rates that actually move the needle
The single biggest reason cleanup crews "fail" is under-stocking. One bag of 5 Amano shrimp in a 100-liter tank is decorative, not functional. As a rule of thumb, aim for:
- Amano shrimp: 1 per 2–5 liters for an active outbreak (drop to 1 per 5–10 L for maintenance). A 60 L tank clearing hair algae wants 15–20 Amanos, not 5.
- Siamese algae eaters: 2–3 juveniles per 100 L. These are a stopgap measure — plan on their appetite declining after 12–18 months, and rehome or accept adult fish that earn their keep elsewhere.
- Nerites: 1 per 20–40 L. They work slowly and methodically on rock and glass; don't expect them to defoliate a plant.
Add the crew gradually (a few days apart) so your filter absorbs the bioload, and check for copper-based medication in the water — it is lethal to shrimp and snails.
Frequently Asked Questions
Will algae eaters starve in a clean tank?
Sometimes — and this is how many otocinclus die. A truly algae-free tank cannot support grazing specialists, so keep a patch of light on a back glass or rock you deliberately let grow, rotate "algae rocks" from a sunny windowsill bucket, and supplement with blanched zucchini, cucumber, or algae wafers. Shrimp are far less demanding: established tanks produce enough biofilm to sustain colonies indefinitely.
Algae eaters or shrimp first — which should I add to a new tank?
Shrimp first, always. Shrimp have a tiny bioload and can graze a new tank the moment algae appears without disturbing the cycle. Otocinclus and especially SAEs need mature, stable water and an existing food supply. The practical order is: cycle the tank, add nerites and shrimp as the first cleanup wave, wait until the tank is stable and at least a few weeks old, then add otos and SAEs.
Will Siamese algae eaters eat my plants?
True SAEs are plant-safe and won't uproot stems or chew healthy leaves. The confusion comes from mislabeled Chinese algae eaters and flying foxes, which are less useful against algae and more disruptive. Verify the stripe-through-the-tail marking when you buy. One exception: an SAE in a starving tank may rasp at tender new growth, so keep them fed with vegetables when algae is scarce.
Can I keep algae eaters with bettas or dwarf shrimp?
Nerites and otos are safe with virtually everything. Amano shrimp are too large for bettas to eat and usually coexist peacefully, though a feisty betta may nip. Cherry shrimp colonies, however, become expensive betta snacks — their shrimplets rarely survive with a betta present. Keep cherry shrimp breeding tanks fishless or with only micro-fish tankmates.
How many algae eaters do I need for my tank?
Start with the stocking section above rather than guessing by volume alone: one nerite per 5–10 gallons, roughly one Amano per 5 gallons for maintenance, otos in schools of at least three, SAEs in trios or larger for tanks 20 gallons and up. Match the crew to the algae you actually have — there is no point adding an SAE if your problem is diatoms, and otos won't touch green spot algae.
Do algae eaters eliminate the need for manual algae removal?
No. Cleaners graze films, dustings, and early-stage growths — but they can't scrape mature green spot off glass, untangle heavy thread-algae mats, or remove established BBA tufts. Think of them as the crew that keeps a clean tank clean after you've done the initial scrub.
Do otocinclus eat brown algae?
Yes — otocinclus are among the most reliable diatom grazers, constantly rasping brown film from leaves and glass. Keep them in groups of six or more in 15–20+ gallon tanks, and only in a fully cycled, stable tank, since they are sensitive to parameter swings. Supplement with algae wafers or blanched vegetables until the tank's algae supply steadies.
Will nerite snails eat brown algae off the glass?
Absolutely — nerites are glass-cleaning machines. Stock roughly one snail per 5 gallons. They cannot reproduce in freshwater, so they never overpopulate. Keep a tight lid on the tank, though: nerites are notorious escape artists that climb out above the waterline.
Will brown algae go away on its own?
Usually, yes. In a new tank, diatom blooms typically peak around weeks 3–6 and fade within 4–8 weeks as the biofilter matures and silicates are consumed. Grazers speed the cleanup, but patience plus water changes and glass wiping resolve most blooms without buying a single animal.
Can I add algae eaters to an uncycled new tank?
No — it backfires. The best diatom grazers (otocinclus, Amano shrimp) are the most sensitive to ammonia and nitrite, and an uncycled tank can kill them within days. Wipe the glass manually and do water changes until the tank cycles, then add your crew to a stable environment where they can thrive.
Do Siamese algae eaters really eat hair algae?
Yes — but only when young. Juvenile true Siamese algae eaters (Crossocheilus siamensis) graze hair algae enthusiastically. By 12–18 months most adults lose interest and prefer fish food. Buy small ones for cleanup duty, and verify the species against the flying fox, which looks nearly identical but eats far less algae.
How many Amano shrimp do I need for hair algae?
For an active outbreak, stock about 1 Amano per 2–5 liters — so 15–20 shrimp in a 60-liter tank. Small numbers won't make a visible difference. For long-term maintenance after the outbreak clears, 1 per 5–10 liters is plenty. Remember shrimp are sensitive to copper medications and sudden parameter swings, so drip-acclimate them.
Will nerite snails eat long hair algae strands?
Not effectively. Nerites are superb at rasping short fuzz and film algae off glass, rocks, and driftwood, but their radula can't shear long strands. Pair them with Amano shrimp: the shrimp handle the strands on plants, the nerites keep hardscape spotless. Their white eggs are harmless but hard to scrape off.
Can I just buy one big algae eater fish instead of a crew?
Almost never works for hair algae. Plecos and Chinese algae eaters are marketed as one-fish solutions but largely ignore hair algae strands, and Chinese algae eaters can turn aggressive as adults. A crew of several small specialists — Amanos plus nerites, with juvenile SAEs for stubborn cases — consistently outperforms any single "algae eater" fish.
Why did the hair algae come back after my cleanup crew ate it?
Because the livestock only removed the symptom. Hair algae regrows rapidly while excess light, unstable CO2, or nutrient spikes (ammonia from disturbed substrate, overfeeding) persist. Cut the photoperiod to 6–8 hours, stabilize CO2 and dosing, keep up weekly water changes, and let the crew hold the line on regrowth — that combination ends outbreaks permanently.
The Bottom Line
The best algae eater for a planted tank is the one that eats your specific algae: young Siamese algae eaters for black beard algae, Amano shrimp for hair algae, otocinclus for diatoms, and nerite snails for green spot algae and film. Avoid the Chinese algae eater and the common pleco entirely, stock gradually to your tank's actual needs, acclimate patiently, and feed just enough to keep cleaners alive without retiring them. Do that, and your cleanup crew becomes what it's meant to be — the finishing touch on a balanced tank, not a patch over a broken one.