Quick answer: Amano shrimp are excellent grazers, but they do not reliably eat every type of aquarium algae. They are strongest on soft green films, biofilm, hair algae, thread algae and other filamentous growth they can pull apart. They may graze young or weakened black beard algae, but established coarse BBA is not a dependable food source. Hard green spot algae and blue-green cyanobacteria are also poor targets for Amanos.
Why Amano shrimp are famous algae eaters
Amanos are larger than most dwarf shrimp and spend much of the day scraping and picking at surfaces. Their size lets them handle strands and particles that smaller Neocaridina may ignore. In a mature planted tank, they move constantly through leaves, wood, rock and filter sponges.
If your aquarium is ready for them, Amano Shrimp can be one of the most useful components of a planted-tank cleanup crew.
Hair algae
Hair algae is one of the best reasons to keep Amanos. Fine green strands are easy for them to grasp, pull and consume. A group can make a noticeable difference when the growth is still manageable.
Severe outbreaks still require correction of light, nutrients and plant health. Shrimp can remove growth without preventing it from returning.
Thread and string algae
Soft filamentous algae is another strong target. Amanos often work through moss, plant stems and hardscape where thread algae becomes tangled. Manual removal first can make the remaining growth easier for the shrimp to control.
Soft green film
Fresh soft film on glass, rocks and leaves is routinely grazed. This is different from hard green spot algae, which adheres tightly and is usually better handled with scraping or Nerite snails.
Biofilm
Biofilm is not one single algae species. It is a complex layer of microorganisms, organic material and microscopic growth. Amanos naturally spend huge amounts of time grazing it, even in tanks that appear visually clean.
That natural food is one reason mature aquariums are better than sterile new setups.
Brown diatoms
Amanos will graze soft brown diatom coatings, especially on plants and textured surfaces. Diatoms are common during the early life of an aquarium and often decline as the tank matures.
Do not add shrimp to an uncycled tank simply because diatoms have appeared. Use the Amano tank cycling guide first.
Black beard algae (BBA)
Amanos have a reputation for eating BBA, but the claim needs context. They may pick at very young, damaged or weakened growth. Dense mature black tufts are often too tough to be a reliable staple.
If BBA is severe, focus on the aquarium conditions that allow it to dominate. Prune heavily affected leaves, stabilize CO2 if you use it, review lighting duration and improve plant health.
Green spot algae
Hard green dots on glass and slow-growing leaves are usually not a strength for Amanos. A scraper or Nerite snail often performs better on hard attached growth.
Our Amano vs. Nerite comparison explains the difference in grazing style.
Blue-green algae / cyanobacteria
Cyanobacteria is not normal green algae and should not be treated as a cleanup-crew food source. Amanos are not a dependable control method. Address flow, organic buildup, lighting and nutrient conditions, and use an appropriate treatment strategy when needed.
Will Amanos eat healthy plants?
Healthy plant tissue is generally not their target. They often appear to be eating a leaf when they are actually scraping algae and biofilm from its surface. Soft dying plant tissue may be consumed because it is decomposing and covered with microorganisms.
Why feeding changes algae-eating behavior
Amanos are opportunistic. A soft sinking pellet is easier to eat than stubborn algae. In heavily fed community tanks, they may spend less time working difficult growth because high-energy prepared food is constantly available.
That does not mean you should starve them. Reduce unnecessary excess food, but continue supplemental feeding when the tank lacks enough natural forage.
How many Amanos do you need for algae?
There is no universal stocking number because tank size, algae production and other livestock vary. A small group in a 10-gallon aquarium can provide visible grazing, while a large planted display may benefit from more. Stock for long-term food availability rather than one temporary outbreak.
Best strategy for using Amanos against algae
- Identify the algae type.
- Correct excess light or unstable plant conditions.
- Remove the worst growth manually.
- Add Amanos only to a cycled mature tank.
- Keep feeding controlled.
- Maintain consistent water changes.
- Use complementary grazers such as Nerites where appropriate.
Frequently asked questions
Do Amanos eat black beard algae?
Sometimes, especially when it is young or weakened. Do not expect them to erase a mature severe BBA outbreak by themselves.
Do they eat hair algae?
Yes. Soft filamentous hair algae is one of their strongest targets.
Do they eat green spot algae?
Usually not efficiently. Nerite snails and manual scraping are often better.
Will Amanos eat all the algae and then starve?
They can run short of natural food in a very clean tank. Supplement with appropriate sinking foods when visible algae and biofilm are limited.
Bottom line
Amanos are excellent algae-control helpers, especially for hair, thread, soft film and biofilm. They are not a universal cure. Identify the algae, correct the underlying tank conditions and use shrimp as one part of a balanced planted-aquarium maintenance plan.
For feeding after the algae declines, continue with our supplemental feeding guide.