The Best Algae Eaters for Any Freshwater Aquarium

What is Algae?

Although algae are dreaded among most aquarium owners, it is actually a normal part of any tank’s ecosystem.  There is no single algae scientific name because algae refers to a group of thousands of species.  Algae is unusual in that it is not considered a fungus, plant, or animal.  These photosynthetic organisms can appear in various shades of brown, black, green, blue, or red.  Algae can be fuzzy, thread-like, or floating. It can form on anything inside your aquarium, including rocks, plants, glass, and equipment.  A certain amount of algae is beneficial to your aquarium, but it can quickly take over if left untreated.

Causes of Algae

Freshwater algae can be caused by an imbalance of light, water, carbon dioxide, and nutrients in your aquarium.  It can also pop up if you have not been regularly changing the tank’s water or have poor circulation.  Also, if you have recently introduced a new plant, it is possible that it already had algae spores.  More often than not, algae is caused by too much light. 

Prevention & Control of Algae

Unfortunately, there is not a single solution to preventing and controlling all types of algae.  There are some general precautions we recommend in order to maintain a healthy aquarium: 

  • Lighting – Do not place your tank in locations that get direct sunlight.  Also, keep your artificial lighting on a maximum of 10 hours per day
  • Water – Routinely change the water in your tank, replacing about 20 percent each time
  • Plants – Algae loves nutrient-rich water, and plants will absorb these nutrients
  • Algae Eaters – These are typically fish, shrimp, and snails that consume algae as food

The best approach to controlling algae is first to identify the type of algae in your tank, and then to tailor your remedy specific to that algae type.  Using algae eaters is a great way to control algae, and we’ll discuss how to find the best algae eaters for your tank in the next section.

What Are Algae Eaters?

“Algae Eaters” is basically a catch-all phrase for any organism that you can keep in your aquarium and eats algae.  Algae eaters, also known as algivores, can be fish, snails or shrimp.  Algae eaters are an essential part of your aquarium’s ecosystem, but please keep in mind that they are not a replacement for routine tank maintenance. 

To find the best algae eaters for your particular setup, look at the Best Algae Eater summary chart below.  If you’re not sure what type of algae you have, we’ve also provided descriptions of the most common freshwater algae types.  

The algae eaters we’ve listed are the best algae eaters for most situations.  However, no aquariums setup is identical.  Tankmates, water quality, nutrient levels, plant varieties, lighting, etc. are all variables that contribute to a tank’s ecosystem.  Sometimes the typical best algae eater won’t work in your situation.  Because of that, we’ve listed alternative algae eaters that have also been known to work. 

Additionally, some algae eaters will eat multiple types of algae but are not necessarily the best algae eater for one particular strain. We’ve made a note of that as well, in case you are experiencing multiple algae strains at one time.

Best Algae Eaters by Aquarium Setup

 Best for Algae TypeMinimum Tank Size (gallons)Maximum Growth (inches)Recommended pHTemperature (Fahrenheit)Suitable for Community TanksWater HardnessFish CompatibilitySuitable for Planted Tanks
Amano ShrimpBlack Beard, Brown, Green Hair526.5-7.560-80YesSoft to Slightly HardSmall to midsize peaceful fish. Avoid aggressive fish-goldfish, cichlids, etc..Yes
American FlagfishBlack Beard, Brown, Green Hair, Staghorn102.56.7-8.266-72SomeSoft to HardFast and narrow-bodied fish--Danios, Tetras, Swordtails, etc.Hardy Plants only; Will Eat Soft-Leaf Plants
Apple Snails (aka Mystery Snail)Blue-Green, Multiple1027.6-8.475-81YesSoft to Slightly HardOther peaceful tank mates-Tetras, Guppies, Killifish, etc.Yes, If Diet Supplemented with Vegetables
Black MollyBlue-Green, Multiple2057.5-8.270-80YesSlightly Hard to HardOther peaceful tank mates- Bigger Tetras, Guppies, Gouramis, etc.Hardy Plants only; Will Eat Soft-Leaf Plants
Bristlenose PlecoMultiple2566.5-7.573-85YesSlightly HardCan be housed with most fish in a community tank.Yes
Cherry ShrimpBrown, Green Dust, Multiple21.66.5-8.065-85YesSoftPeaceful fish-Tetras, Otocinclus Catfish, etc. Avoid large fish such as Angelfish, Cichlids, etc.Yes
Ghost ShrimpGreen Dust, Green Hair526.5-8.070-85YesSoft to Slightly HardSmall less aggressive fish. Avoid keeping them with large fish; they are likely to eat them.Yes
Nerite SnailsGreen Hair, Multiple517.5-8.572-78YesSoft to Slightly HardMost community fish. Avoid Loaches, Cichlids, Crayfish, etc.Yes
Otocinclus CatfishBrown1026.5-7.571-80YesSoft to Slightly HardAny peaceful community fish. Not compatible with large Cichlids.Yes
Rubber Nose Pleco, Bulldog PlecoBlue-Green, Brown, Green Dust, Green Spot, Multiple2516.5-8.565-85YesSoft to Slightly HardPeaceful community fish-Tetras, Gourami, Cory Catfish, etc.Yes
Siamese Algae EaterBlack-Beard, Brown, Green Hair, Staghorn, Multiple3066.5-775-79YesSoft to Slightly HardPeaceful community fish-Tetras, other Barbs, Plecos etc.Yes

Types of Algae

Black Beard Algae aka Black Brush Algae (Audouinella)

It’s usually black or dark purple and typically grows on plants and equipment.  The texture will resemble carpet, growing as short tufts, or hairs. It usually occurs because of high carbonate hardness or low carbon dioxide levels.  Unfortunately, Black Beard Algae is one of the hardest strains to get rid of.  It’s impossible to clean the plant leaves manually; you must remove each leaf individually.  You can also remove equipment and clean it chemically, but this can be dangerous to your fish if not done correctly.  We prefer to use black algae eater.  Siamese Algae Eaters, Amano shrimp, Nerite snails, Black Mollies, and American Flagfish are what eats black beard algae.

Blue-Green Algae (cyanobacteria)

In actual color, this can show up as a bluish-green, but also as a light red or pink.  It should be noted that this is actually a bacteria but is typically classified as algae in the home aquarium realm.  It grows in slimy layers over decoration, equipment, rocks, and substrate.  A tell-tale sign of blue-green algae is a strong, musty odor. Poor circulation and low water quality are usually to blame for this algae.  It best propagates in anaerobic (low oxygen) environments.  As for what eats cyanobacteria, most fish won’t come near it, as it is harmful to them.  However, some aquarium owners have had success using Plecos, Apple snails, and Black Mollies.

Brown Algae, aka Brown Dust Algae (diatoms)

If you’ve had an aquarium for any length of time, you’ve most likely encountered this type of algae.  Brown algae will almost always occur in new tanks.  It thrives in low-light conditions, tap water with high silicates, and high phosphates.  It usually appears as powdery or fluffy and can show up on glass, decorations, and equipment.  This algae strain isn’t one to worry about as it often goes away on its own.  If you notice it getting progressively worse, there are many brown algae eaters from which to choose.  Nerite snails, Otocinclus catfish, Amano Shrimp, Siamese Algae Eaters and Bristlenose, Bulldog, and Rubber Nose Plecos will all eat brown algae. 

Green Dust Algae

You will probably first notice this strain of algae on your glass because it will block the view.  It tends to grow on smooth surfaces, so it can appear on equipment as well as your glass.  It seems to be caused by too much light or the introduction of new plants/equipment with spores.  It appears as a very fine green dust and moves easily in water.  Make sure not to confuse it with Green Spot algae, which appears as large, green circles.  If you are not sure, try pushing against it:  if it comes off easily, it is most likely green dust algae. If it resists, it is most likely Green Spot algae.  The best algae eaters for green dust algae are the Otocinclus catfish, Nerite snails, and Bristlenose, Bulldog and Rubber Nose Plecos.

Green Hair Algae, aka Thread Algae (Oedogonium)

This strain is green in color and can appear as delicate, inch-long strands or short clumps of green hair.  It can grow very quickly if left untreated.  It typically appears on slow-growing plants.  Green Hair algae usually occur in newer aquariums where the nutrients are not yet balanced.  The best Green Hair algae eaters are Nerite snails, Amano shrimp, Ghost shrimp, Siamese Algae Eaters, Black Molly fish, and American Flagfish.

Green Spot Algae (ColeochaeteOrbicularisGSA)

This strain of algae is exactly what it sounds like:  flat, green spots that grow on the glass, plants, or equipment.  It will usually show up on your glass.  It is easily distinguished from Green Dust because Green Spot algae will be difficult to scrape off.  It is generally caused by too much light.  You can use a razor blade (on glass) or scouring pad, but we prefer to use creatures as our green spot cleaners.  The best ones are the Bristlenose, Bulldog and Rubber Nose Plecos, Nerite, and Apple snails.

Staghorn Algae (Compsopogon sp.)

In color, this strain is a bluish-gray, grayish-green, or nearly black.  It grows in thick hairs that resemble a tree branch or a deer’s antlers.  It will appear on any surface in your tank and is usually caused by too much light, low carbon dioxide, or poor water circulation.  Most of the time, reducing the daily light hours will help with Staghorn Algae.  Most algae eaters will not eat it.  However, many owners have had luck with real Siamese Algae Eaters and American Flagfish. 

Best Algae Eaters

Amano Shrimp

These are probably the best algae-eating shrimp available.  They are great for beginning aquarium owners because of their hardy nature.  They act like tiny garbage disposals, eating everything from algae to decaying plants.  They generally will not eat live plants, and they are one of the few black beard algae eaters.  Amanos will also eat Green Hair and Brown algae.  Their larger size means they are better able to defend themselves than other shrimp species. Don’t be surprised if they change from a whitish color to blue; this happens because of their algae-rich diet.  Also, make sure to check your copper levels, as copper is toxic to invertebrates. 

American Flagfish

This algae eater is named after the American Flag because of its unique coloring.  It is the best algae eater for Black Beard, Green Hair, and Staghorn algae.  This fish loves to find places to hide, so make sure to provide it with plenty of driftwood and rocks.  It’s best housed with hardy plants (java fern, hornwort) as it will eat soft-leaf plants.  This fish is semi-aggressive (nips fins) but can work in a community tank with narrow-bodied and fast-swimming tank mates.

Apple Snails, aka Mystery Snails

These little guys are very popular with aquarium owners because they do well with most types of fish; anytime they sense danger, they simply go inside of their shells.  They will eat most types of algae and have been known to eat blue-green algae, which most others will stay away from.  However, keep in mind that they will also eat plants.  If you supplement their diet with blanched vegetables, you can sometimes avoid this.  Otherwise, they are best suited for a non-planted tank.

Black Mollies

This velvety black fish isn’t typically thought of as an algae eater, but it will occasionally nibble at all types of freshwater algae.   Also, these fish are one of the few that will eat blue-green algae.  Black Mollies are excellent community fish, but when housing with other Mollies, make sure to keep a male to female ratio of 1 to 3.  Black Mollies do best in densely planted tanks and need high-mineral water. 

Bristlenose Pleco, aka Bushymouth Catfish

These fish are excellent at blending into the background and will sit undisturbed for countless hours.  This is a hardy fish, which means it’s a solid choice for beginning aquariums. They are also some of the best algae eaters you can find. They do seem to prefer Green algae to Black Beard and brown, but they still nibble on it all.  Their unique sucker mouths can get algae off of rough and smooth surfaces.  They prefer darkness, so provide them with caves, moss, and driftwood. Apart from being an excellent hiding place, the wood fibers in driftwood aid their digestion.  In general, they are good community fish and do well in planted tanks.

Cherry Shrimp

There’s no mistaking these shrimp with others—their vibrant red color is a dead giveaway.  These are another hardy shrimp, making them suitable for beginners.  They do well in community tanks with other peaceful tank mates.  They also love to hide, so you will want to provide them with driftwood and moss.  Also, make sure to use a sponge filter; otherwise, they will get sucked in.  This species will nibble on all types, but it’s the best algae eater for soft green and brown algae.  Because of their small size, they can squeeze into the tight nooks of your tank, making them some of the most versatile freshwater algae eaters. 

Ghost Shrimp aka Glass Shrimp, Grass Shrimp

Usually, Amano and Cherry shrimp will make better algae eaters than Ghost shrimp.  However, as we mentioned earlier, sometimes the typical best algae eaters don’t always work for everyone.  If that is your situation, we suggest trying Ghost shrimp.  Like Cherry shrimp, these are little guys that can maneuver into tight spaces.  They are not just algae eaters—they will eat fish excrement, dead fish, dead plants, and leftover fish food.  They seem to love “fluffy” algae types, like Green Hair or Green Dust.  They do well in community tanks with other peaceful tank mates.  Because they are translucent, we think they look great in tanks with a black substrate.

Nerite Snails

These little guys are visually appealing as well as beneficial to your aquarium.  Nerite Snails are perfect for a beginning aquarium enthusiast because they require little care once you’ve added them to the tank.  They typically grow to about 1 inch in diameter and are safe in a community tank with any fish, plants, or shrimp.  There are several species of Nerite snails, including Black Racers, Sun Thorn, and Tiger Eye. Nerite snails eat nearly every strain of algae and are the best snails for hair algae.  They are a bit picky when it comes to Green Spot Algae.  They tend to leave Green Spot Algae on glass in larger tanks but will happily eat it off rocks.  Nerite Snails will breed in Freshwater tanks, but the eggs will not hatch.  They are sensitive to copper, so make sure to check the levels if you use tap water.

Otocinclus Catfish, aka Dwarf Sucking Catfish

If you are looking for small algae eaters, Otocinclus catfish are a great choice.   They grow to a maximum size of about 2 inches, which makes them ideal for smaller tanks.  They look very similar to Chinese Algae Eaters but are more peaceful. Otos do well in community tanks with other peaceful species.  Make sure to equip your tank will plenty of leaf litter and driftwood.  These are great brown algae eaters and will sometimes eat soft green algae, like Green Dust.  Usually, they will not eat Green Hair or Green Spot algae. 

Bulldog Pleco & Rubber Nose Pleco

Plecos are some of the best algae eaters that aquarists can find.  However, some varieties can grow up to 2 feet long, which is why we recommend the Bulldog or Rubber Nose.  These species are among the smallest plecos that also make the best algae eaters.   These are hardy fish, so they are suitable for beginners.  You will want to include hollow logs and caves in your aquarium setup because this species likes to hide.  Also, this is a peaceful fish that does well in community tanks.  Plecos will eat Brown algae, Green Dust algae, Green Spot algae, and some will eat Blue-Green algae.

Siamese Algae Eater

Well, this one is in the name, right?  Siamese Algae Eaters are among the most popular algae eaters for aquarium owners.  These are peaceful fish that do well in planted aquariums.  It can grow up to 6 inches, so you will want to make sure your tank is large enough.  This species will eat the dreaded Black Beard algae, as well as Brown, Green Hair, and Staghorn algae.  When buying, make sure you are getting a true Siamese Algae Eater.  Many tank owners have discovered that they actually purchased a Siamese Flying Fox that was mislabeled.  Unlike the Siamese Algae Eater, the Flying Fox can be aggressive and may pose a danger to tank mates and plants.  If you are unsure when shopping, here are a couple of things to look for:  the black stripe on the Flying Fox ends where the tail fin begins, and it’s usually smoother; the Siamese Algae Eater has a stripe that stretches to the end of the tail fin, and it’s a “rougher” patterned-stripe.  If you’re still having trouble distinguishing between the two, here’s a YouTube video that helps to identify them.

FAQ’s on Best Algae Eaters

How long does it take for algae eaters to work? This depends on several factors, most importantly, your tank size and the types of algae eaters you are using.  Something like a Siamese Algae Eater will have a 20-gallon tank cleaned in just a few days.  A few Nerite snails can get your glass clean in one afternoon.  We’ve also seen a colony of five Amano shrimp completely clean off a 3-foot log covered in Green Hair algae in a 24-hour period.

How many algae eaters do I need? A good rule of thumb is one inch of algae eater per 5 gallons of water.  Something to keep in mind is that once all of the algae has been cleaned, you will usually need to supplement the algae eater’s diet. It depends on the species, but examples include blanched vegetables or algae tablets purchased from a pet store.  It is usually best to err on the side of too few rather than too many so that the tank’s ecosystem remains balanced.

Do Bettas get along with Siamese Algae Eaters? A single male Betta can peacefully share a tank with a Siamese Algae Eater, and other community fish for that matter.  Keep in mind that the minimum tank size for a Siamese Algae Eater is 30 gallons, and you want to make sure that you purchase a true Siamese Algae Eater.

What do algae eaters eat? Once the algae in your tank have been significantly cleared, you may need to supplement your algae eater’s diet.  The supplemental food will depend on the specific algae eater in question.   Here are a few examples:  shrimp will eat dead fish and plant matter, or shrimp pellets purchased from a pet store.  Snails will eat dead plants and fish waste.  They also love vegetables, such as blanched lettuce or kale.  American Flagfish will eat brine shrimp, flake food, or white worms.  As a general rule, algae eaters are not picky and will be happy grazing on a variety of food.

Why do my algae eaters keep dying? There could be a variety of reasons.  First, make sure you didn’t go overboard on algae eaters.  Too many in one tank causes more competition for algae, which is the algae eater’s primary food source.  Second, check your that your aquarium conditions are suitable for that particular algae eater.  Water temperature, pH, and hardness all need to be just right to be suitable homes for aquatic life. 

What are the best algae eaters for a small tank? For a small tank, you can’t go wrong with shrimp.  Cherry shrimp only need a minimum 2-gallon tank, and Amano and Ghost shrimp only need 5 gallons.  Amanos are probably the best algae eater for most aquarium setups, as they clean a wide variety of algae types.  Nerite snails are also great.  They only need 5 gallons and will vacuum up algae in your tank until it looks new again.

Also read – Best Aquarium Stand for Fish Tank of Every Size

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