If scraping algae off your glass makes you sad, consider getting an algae eater for your aquarium.
I’m not saying that your algae eater will keep your tank perfectly clean and clear of algae, but they definitely can help get the green stuff under control.
And, some of the best freshwater algae eaters are fascinating to watch and enjoyable to keep.
Algae eaters come in a variety of sizes, and this article will review which freshwater algae eaters are best for tanks ranging from 2 gallons to 100+ gallons.
Size, aesthetics, and algae eating efficiency are the main factors considered in this article, but picking the right algae eater for you also depends on which fish you plan keep with your algae eater.
The Best Freshwater Algae Eaters
Most of the fish and invertebrates listed in this article work well in a community tank, but some are better kept alone or exclusively with other members of their species.
Picking the right algae eater is not only about selecting the right sized fish for your tank, it’s also about choosing an interesting and enjoyable fish to keep.
Temperature: 74-80 F (23.33-26.67 C)
Tank Size: 5-20 Gallons
My overall top pick for the best algae eater is the personable Otocinclus.
Also known as a Dwarf Sucker, Otocinclus combine algae eating efficiency with a small body size, making them ideal for nano tanks.
Growing to maximum size of about 2 inches, Otocinclus fill the need for a small algae eater in tanks ranging from 5 gallons to 20 gallons.
Otocinclus are shy fish and should be kept in groups of 5 or more to reduce stress.
But, keeping a pair of Otocinclus in a 5 gallon is certainly doable, especially if the tank only houses a single fish, like a betta fish, or is a dedicated shrimp tank.
Otocinclus, or “Otos,” are peaceful fish and therefore make excellent tank mates for a variety of other tropical community fish.
While, Otos will gorge themselves on the available algae in your tank, providing a quality algae wafer to supplement their diet is important for the health and longevity of your fish.
When picking out an Oto for your tank, ask whether the Otos on display are wild caught or captive bred.
And ask how long the fish have been in the store.
Otos that have survived in a fish store for 2 weeks or more have a much better chance of surviving in your home aquarium.
Buying captive bred fish is vital to preserving wild populations, and in the case of Otos, the methods used to capture them in the wild too often result in fish that die within days of being taken home by an aquarist.
So, to save you frustration and to save wild Otocinclus populations, try to find well established, captive bred Otos for your tank.
2. Bristlenose Catfish
Temperature: 72-80 F (22.22-26.67 C)
Tank Size: 15-25+ Gallons
Bristlenose catfish, also called bristlenose plecos or bushynose catfish, are of the genus Ancistrus, and are therefore not true “plecostomus” like the common pleco.
Bristlenose catfish are so named because the front of their snout (for lack of a better word) is covered in fleshy branches or tentacles.
Male bristlenose typically have larger tentacles that extend up the head, while females have smaller tentacles around the snout area.
Bristlenose catfish are amazing algae eaters and can quickly clear algae off of glass, decorations, and driftwood.
The wonderful thing about bristlenose catfish, as compared to the common pleco, is their reasonable size.
Bristlenose catfish grow up to 6 inches in length, but many remain around 4 inches in home aquaria.
In contrast, common plecos can grow to over 12 inches in length, and will rapidly outgrow most tanks.
Juvenile bristlenose catfish are perfect algae eaters for tanks between 15-25 gallons, but will need an upgrade once they reach their full size.
3. Common Pleco
Temperature: 72-80 F (22.22-26.67 C)
Tank Size: 100+ Gallons
The common pleco (Hypostomus plecostomus—say that 5 times fast) is what many think of as the quintessential algae eater in home aquariums.
All too often, these plecos are sold as babies, looking like the perfect addition to a newly setup 10 gallon tank.
But, the unsuspecting buyer will eventually discover that these plecos become monsters pretty quickly (reaching between 15 and 24 inches), and really need to live in 100+ gallon tanks or ponds.
Common plecos are best avoided unless you have or plan to have a gigantic aquarium.
That being said, common plecos are stunning to look at.
They have armor plating, huge eyes, and kind of look like a dinosaur.
If you have they room, a common placo makes an excellent algae eater, otherwise check out the bristle catfish, which stays a much more reasonable size.
One thing to note is that while plecos are known as algae eaters, they are also opportunistic and will eat small fish and shrimp if they get the chance.
4. Hillstream Loach
Temperature: 68-76 F (20-24.44 C)
Tank Size: 20-40+ Gallons
Hillstream loaches (of the genus Sewellia) are one of the most unique looking algae eaters available in the aquarium hobby.
The body of a hillstream loach is suprisingly flat, giving it an alien like appearance (think facehugger).
This helps the fish remain attached to rocks and wood even in environments with strong water flow, like a stream.
In the wild, Hillstream loaches live in fast flowing, oxygen rich, tropical rain forest streams in Asia.
In home aquaria, water flow tends to be much weaker than what is found in their native habitat.
So, a common question about hillstream loaches is whether these fish can be kept in low flow aquariums, with basic filters like a hang on back or sponge filter.
The answers is that hillstream loaches appear to be most active in high flow tanks, where total water turnover is around 10-20 times per hour.
Many aquarists find that they are able to keep hillstream loaches in tanks with less flow, but it is unclear if the loach is thriving or just surviving under these conditions.
Ideally, a tropical fish’s native habitat would be replicated by the home aquarists as much as possible, so providing a high flow portion of your tank (with a powerhead) is best, and will likely reduce stress levels in your fish.
Hillstream loaches have been known to jump out of aquariums, so having a lid is advisable.
While these fish are voracious algae eaters, supplementing their diet with spinach leaves and a quality algae wafter is important.
5. Amano Shrimp
Temperature: 70-80 F (21.11 – 26.67 C)
Tank Size: 2-100+ Gallons
My fifth pick for best algae eater is the Amano shrimp.
These freshwater shrimp are fantastic algae eaters and are also fascinating to watch as they scurry through the tank looking for morsels to eat.
Made famous by world renowned aquascaper Takashi Amano, these shrimp are extremely popular among planted tank enthusiasts and aquascapers for their algae eating abilities and also for the natural aesthetic these shrimp provide.
If your goal is a nature style aquarium, these shrimp are the perfect choice.
Amano shrimp can grow to a sizable 2 inches, which makes them excellent tank mates for fish that might eat smaller shrimp species.
6. Cherry Shrimp
Temperature: 72-80 F (22-27 C).
Tank Size: 2-100+ Gallons
Cherry shrimp (Neocaridina davidi) are freshwater shrimp named for the bright red color of their carapace (shell).
This shrimp species is actually available in a wide range of colors, including green, blue, orange, and yellow, but the common name of “cherry shrimp” has stuck and so—no matter the color—this freshwater shrimp is often referred to as a cherry shrimp.
Cherry shrimp are excellent algae eaters, and a large group can quickly clean up a small tank.
While they tend to avoid eating hair algae, they make an excellent cleanup crew and are arguably the most visually stunning algae eater in this list.
Cherry shrimp, unlike their cousins the crystal shrimp, are about as easy to care for as tropical community fish.
They appreciate stable water conditions, but can tolerate mild swings in parameters (at least in my experience).
The trickiest part about keeping cherry shrimp is choosing appropriate tank mates for them, as many fish see them as a snack.
If you want to learn more about tank mates for these shrimp or learn about other species of freshwater shrimp, check out my ultimate shrimp tank guide.
7. Siamese Algae Eater
Temperature: 75-80 F (23.89 – 26.67 Celsius)
Tank Size: 20+ Gallons
The Siamese Algae Eater (typically Crossocheilus langei; Crossocheilus siamensis; or Crossocheilus oblongus) is perhaps best known for being one of the few fish that will eat black beard (or brush) algae and hair algae.
If you have never battled black beard algae (*shudders*), then count yourself lucky, it’s really hard to eliminate.
But, Siamese algae eaters can help you defeat it.
Some individual fish seem more motivated than others to eat the stuff, but if you are fortunate enough to find a genuine Siamese algae eater, he/she will help free your tank of the black beard algae for good.
The main downside of this fish is finding the real deal, as they are frequently mislabeled and misidentified at fish stores.
In fact, instead of taking home a Siamese algae eater, many unsuspecting aquarists bring back a Flying Fox (Epalzeorhynchos kalopterus).
To make things more confusing, Siamese algae eaters are sometimes called “Siamese Flying Foxes,” which means that any fish labeled “Flying Fox” at the fish store is suspect.
False Siamese Algae Eaters also exist (Garra cambodgiensis), as well as Chinese Algae Eaters (Gyrinocheilus aymonieri), adding additional confusion.
If you want to take a deeper dive into the distinctions between these similar looking fish, take a look at TheKrib’s article on algae eaters.
The best way to identify a true Siamese Algae Eater is to make sure the fish has:
1) an unbroken black stripe extending from its tail to the tip of its nose (the stripe divides the middle of the tail);
2) Translucent fins, especially the dorsal fin; and
3) No red coloration along the tips of fins.
Siamese algae eaters are perfect for planted tanks, they will eat algae off of plant leaves and perch on top of larger plants in a way that is unusual for freshwater fish.
If you can find one, and have a tank of 20 gallons or larger, get one.
8. Mystery Snail
Temperature: 70-80 F (23.89 – 26.67 Celsius)
Tank Size: 3-20+ Gallons
Snails are often looked at as a nuisance in aquariums, and the little ones that seem to take over your tank after introducing a new plant certainly live up to that reputation.
But, some of the best algae eaters in aquariums are snails.
And some of the best algae eating snails are “Mystery snails.”
Mystery snails (Pomacea brigesii) are a very underrated algae eater, they are interesting to watch and make peaceful tank mates for a wide range of tropical fish.
During the day, these snails often appear to be doing nothing, but at night they will cruise around your tank removing algae from plant leaves, glass, and décor.
Reaching a little over 2 inches in diameter, mystery snails are perfect algae eaters for tanks where aquarium shrimp would be gobbled up.
A large mystery snail is typically left alone by most aquarium fish.
There are exceptions, so monitor your snail and remove it if your fish start bumping it off the glass or trying to rip its eyes out.
But, most of the time, your mystery snail will be left alone to slowly, but steadily, remove algae from your tank.
Providing your snail with supplemental food, like algae wafers, is a good way to help ensure its survival.
The algae eating fish discussed in this article are not the only algae eaters in existence.
Numerous fish will pick at algae, though they tend to be much less efficient than the fish and invertebrates mentioned above.
For example, Mollies often pick algae off the glass and décor.
But, Mollies are much less efficient than a dedicated algae eater like an Otocinclus, or even a group of cherry shrimp, so they didn’t officially make the list of best algae eaters.
The common pleco and the bristlenose catfish are also not the only “suckerfish” types that eat algae.
A huge variety of plecos and sucker catfish exist, many with fascinating colors and fin shapes, but they tend to be more pricey and hard to find.
Thankfully, the fish in this article are relatively common and may be easy to find, depending on where you live.
If you are thinking about adding an algae eater to your tank, I hope this article gave you a better idea of which fish to choose.
If you are thinking about setting up a small tank, like a 5 gallon, and need more ideas for which fish can live in small tanks, check out my article on best fish for a 5 gallon tank.
As always, stay zen.