7 Amazing Freshwater Algae Eaters (And One to Avoid!)

Best Algae Eaters

Algae is a constant problem in aquaria. Because of the issues it can cause, you may need to make sure that your tank is stocked with a cleanup crew alongside your flashier fish. There’s a lot of misconceptions surrounding algae eaters, so read on for some great ideas and some things to avoid.

1. Common Plecostomus

Common Plecostomus

  • Maximum Size: 18-24″
  • Minimum Tank Size: 50g
  • Care Level: Beginner
  • Special Requirements: Driftwood

The Common Pleco is often sold to the unwary, who think of them only as an algae eater. The truth is that they’re highly specialized catfish, living out their lives in swift streams where their sucker mouth is a necessity to avoid being displaced.

People often buy their Pleco when they’re only a few inches long. Very inexperienced aquarists are sometimes of the impression that they’ll fit their tank. They won’t; they’ll keep growing for years until they either die in their own waste or reach their adult size.

Plecostomus are easy to keep. They eat detritus and feast upon algae as well. You should also keep them in tanks with driftwood since they rasp on the wood to balance their digestive system. Without it, their stomachs don’t function at 100%.

Plecostomus are very powerful for their size, especially when they begin to get over 6″ in length. They’re armored as well, which makes them the only Plecostomus species that do well with cichlids and other aggressive fish.

They’re a great option for those with larger tanks, but smaller tanks should give these large, impressive fish a miss. However, you’re definitely not out of options, as there’s plenty of variety in algae eaters for smaller tanks.

2. Bristlenose Pleco

Bristlenose Pleco

  • Maximum Size: 4-6″
  • Minimum Tank Size: 10 gallons
  • Care Level: Beginner
  • Special Requirements: Driftwood

The Bristlenose Plecostomus is a smaller variety of Pleco. While they’re not the smallest overall, they’re easy to find and care for. They’re also much cheaper than some of the high-dollar Pleco species that are in the same size range.

Bristlenose Pleco are suitable for small, but not nano-sized, tanks. They’ll still need driftwood, but they also seem to be more prolific algae eaters than the Common Pleco. They’re nearly as ubiquitous as Common Pleco in stores these days and don’t have any other specialized requirements.

They also make great cleaners for larger community tanks if you add multiples. One per 20-30 gallons is a good number to shoot for if you need a cleanup crew. They’re compatible with most fish and are rather hardy critters overall.

Their size, active nature, and admittedly good looks make them a favorite for many. For newbie aquarists, they’re the best option for algae eaters. That’s doubly true for smaller tanks.

3. Otocinclus Catfish

Otocinclus Catfish

  • Maximum Size: 1 ½”
  • Minimum Tank Size: 5 gallons
  • Care Level: Intermediate
  • Special Requirements: Aged Tank

Otos are used in the majority of small planted tanks. Their size makes them well-suited to hanging out in nano-tanks, but many people have trouble making them thrive.

The key to making Oto do well is understanding their needs. While Pleco actively eat algae and detritus, Otos subsist on algae and biofilm. Biofilm is a manageable part of any tank, but it only begins to occur once the tank has stabilized post-cycle.

Otos are easy to care for… as long as the tank is matured. They eat a surprising amount of algae, but you shouldn’t place them in a brand new tank since they won’t have a food supply. Few will even take algae wafers.

Once the tank matures? They’re excellent fish for cleaning things up. They’re not truly voracious eaters, but a trio per five gallons will keep things tidy in a well-balanced tank. Alongside the usual suspects in invertebrates… well, they’re essential.

4. Ramshorn Snail

Ramshorn Snail

  • Maximum Size: 1″
  • Minimum Tank Size: 1 gallon
  • Care Level: Complete Newbie
  • Special Requirements: None

Of the common snail varieties, Ramshorn Snails are the best looking and best algae eaters. They have a malign reputation in some circles, but the same qualities that make them a pain also make them an excellent algae eater.

Ramshorns breed prolifically. Since they’re hermaphroditic, you only need two snails to start breeding. And breed they will, these snails lay tons of eggs frequently, which hatch in a few days to create a ton of miniature snails.

Depending on the tank, you may have more or less overpopulation. Many fish like to eat the tiny snails, creating an inbuilt population control. In heavily planted tanks, however, many will reach adulthood.

Test your nitrates if you see a sudden spike in the snail population. High nitrates often cause them to breed more prolifically, creating a monitor for nutrient spikes in your tank’s water column.

Ramshorns have a few color morphs. The pink and grey varieties are most common, but they can all breed amongst each other. They’re attractive at larger sizes, but population control is a must. If you can manage that, they’ll survive in any water conditions and create an efficient cleanup crew with no extra work required.

5. Cherry Shrimp

cherry shrimp

  • Maximum Size: 1 ½”
  • Minimum Tank Size: 3 gallons
  • Care Level: Beginner
  • Special Requirements: None

Cherry Shrimp or Neocardina davidi are the most common dwarf shrimp in the tropical aquarium hobby. They’re easy to care for, lively, and come in a wide range of colors. All of that together leaves them at the top of the list for many aquarists.

Cherries are among the easiest creatures to care for. They’re extremely hardy, breed prolifically, and don’t require a ton of food. They’ll readily eat algae around the tank, as well as sifting through the bottom of the tank to find discarded bits of food.

There’s power in numbers here. In an established tank, you can keep roughly 2-3 per gallon without adding significantly to the bioload. It’s not uncommon for this number to reach 5-6 per gallon in dedicated shrimp tanks.

They’re not the most prolific algae eating shrimp, that title belongs to the Amano Shrimp, but they’re fun to keep and do a great job. You’ll just need more of them per gallon of water.

6. Nerite Snail

Nerite Snail

  • Maximum Size: 1 ½”
  • Minimum Tank Size: 1 gallon
  • Care Level: Beginner
  • Special Requirements: Hard Water or Calcium Supplementation

Nerite Snails are beloved for their striking patterns and large size. They have a hidden benefit for the aquarist looking to capitalize on their algae eating abilities. However, they’re a bit tricky to breed. Essentially, you’ll need brackish water.

That means you can purchase a couple of Nerites without needing to plan for population explosions. Ramshorn and bladder snails become part of a tank’s ecosystem entirely, Nerites are about as far outside of it as most fish can be.

Nerites are easy to care for. Plop them in and check on them. You’ll need to keep an eye on their shells, however. They require a considerable amount of calcium to form their shell, and it will bleach and thin if levels are too low. A bit of spinach or kale will fix the problem if your water isn’t hard enough.

Overall, Nerites are a low impact, algae-eating machine. They’re not as prolific eaters as Ramshorns, but many people feel it balances since they won’t breed unpredictably. Give them a shot instead if you’re worried about having to take stronger population control measures with other species of snail.

7. Amano Shrimp

Amano Shrimp

  • Maximum Size: 2″
  • Minimum Tank Size: 3 gallons
  • Care Level: Beginner
  • Special Requirements: None

Amano Shrimp have a reputation as busy workers. It’s well deserved as well. It’s rare to see an Amano sitting idle in your tank; they eat constantly. They’re also clear for the most part, providing minimal visual impact in cases where the greenery is the most important part of the tank.

Amano Shrimp have another advantage to some. They don’t breed like Bee or Cherry Shrimp, both of which breed as long as they’re alive. Their breeding process is a bit much for the casual aquarist.

Amano Shrimp are hardy, requiring nothing in the way of specialized care unless you’re breeding them. They’ll stay out of the way much of the time, and they’re better with slightly larger community fish than Cherry Shrimp due to their larger size.

They’re a classic for planted tanks. Give them a shot if you like plants but don’t like the idea of brightly colored Neocardina sp. flitting around the tank. Their bland appearance belies a hard-working, prolific algae eater.

Avoid At All Costs-The Chinese Algae Eater

Chinese Algae Eater

One of the cruelest tricks of the aquarium trade was naming the Gyrinocheilus aymonieri as an algae eater. The technically accepted name is the Siamese Algae Eater, but most places I’ve seen call them the Chinese Algae Eater. The gold variation above is termed the Gold Chinese Algae Eater, but habits and physiology are interchangeable apart from color.

They start out cute. They grow swiftly, and they’ll often annihilate all of the algae in a tank. Problems begin when they hit 3″ or so, and persist throughout the fish’s lifetime.

As they grow older, they eat far less algae than they did while younger. Instead, they begin to switch to a carnivorous diet. Their sucker mouth isn’t an adaptation to eating algae… it’s an adaptation to its native environment of fast-moving streams.

They also become territorial and aggressive. They can kill fish much larger than themselves by sucking off their slime coating before they feed on the body. They’re even worse with each other.

Are they a fish with no good qualities? No. They’re fun to watch and housed alone or with suitable companions. They’re a solid fish.

But if you buy one as an algae eater, you’re going to end up with a large and aggressive headache. As if that wasn’t enough… well, they quit eating algae as they get bigger, and they’ll eventually reach a foot in length.

There is a similar fish, which is an amazing algae eater. The Flying Fox can be hard to tell apart from the CAE, and other species, but it’s one of the best algae eaters around. It even eats brush algae! The problem lies in finding a real Flying Fox, since even the dealers are sometimes unaware they’re selling you the wrong fish.

Give CAE a pass unless you know what you’re going in for, and be extremely careful if you choose to add a Flying Fox to your tank.

Algae Eater FAQs

Do All Tanks Need Algae Eaters?

Not necessarily. Instead, you can focus on making sure you have parameters well in order and cleaning up the small amount that shows up anyways naturally. That said, you’ll require more frequent water changes and a closer eye on water chemistry.

When is Algae Bad?

When it’s “blue-green algae” or Cyanobacteria. These slimes can be dangerous. Otherwise, algae isn’t a bad thing; it’s simply there and can be a bit unsightly. It can be a good indication of general nutrient levels, however, and in an established tank, they can often prompt a test. In a new tank, don’t rely on algae to let you know what’s happening.

Does Algae Make My Tank Smell?

It can, but smells are often the products of pollutants instead of the algae itself. If your tank smells, you’ll need to up your water change game, rather than just drop in some new snails.

What Other Solutions to Algae Are There?

Algae almost always indicates excessive nutrients. For instance, brown algae are intrinsically tied to nitrates and often occur in droves when a tank first cycles before mellowing out. Cyanobacteria usually indicates a lack of oxygen in the water, while green spot algae may indicate low Phosphorous or CO2. The biggest culprit I’ve seen is people running their tank lights too long; they keep it under 12 hours. 8-10 hours is the sweet spot.

Are Chemical Fixes a Good Idea for Algae?

They can be, and it depends on how you define a chemical fix. What I don’t recommend is dumping in an algaecide and hoping it works. This just masks the underlying problem, and the rotting algae may only compound things as time goes on. Modifying nutrient parameters is a much better chemical approach, giving a tank just the little push it needs to lower algae growth.

Which is the Best Algae Eating Fish?

I recommend the following:

  • 50 gallons +: Common Pleco
  • 10-40 gallons: Bristlenose Pleco
  • <10 gallons: Oto Catfish

Those guidelines won’t lead you astray since all of the fish are relatively mild but tough enough to handle anything that will fit in the same tank.

Why Didn’t You Recommend the Siamese Flying Fox?

If you’re aware of the species, then you probably know that copycats are more common than the actual fish. The Flying Fox is a marvelous algae eater, possibly the best you’ll find for home aquaria, but I’m always uncomfortable recommending it to new aquarists. You’ll need to be able to distinguish it from both the Chinese Algae Eater and Siamese Algae Eater, as well as any other lookalikes. Do your research if they’re your choice!

Get Your Cleanup Crew in Order

Our cleanup crews have a very important job: they keep our tanks nice and pure. While they can’t do it all on their own, they’re often the first-line defense against algae in your tank. The fact that they clean up uneaten food is just a bonus. So, how are you going to arrange your cleanup crew?

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