Do Fish Eat Algae? What kind of Fish Eat Algae?

Recently, I had been noticing the uncontrollable infestation of algae in my fish tank. Even though some algae is good for your aquarium, too much of it can become a problem for the fish living there.

So I started my research on how to maintain the perfect balance that exists in a fish’s natural habitat.

And here is what my research told me.

Do fish eat algae? Yes, they do. There are different types of fish that are known as algae eaters or the ‘clean up crew’, who help in getting rid of excessive algae in your tank. These fish are the safest, most effective method of keeping the algae infestation at bay. 

If you, like me, are a newbie fish parent, wondering about the exotic world of aquatic life, then here is everything you need to know about algae, fish and how they can fatten up on the seemingly polluting plants.

Fish and Algae: Understanding the Delicate Balance

Algae in a fish tank? It is a pretty common sight and one that bugs aquarists a lot. Not only does it make the tank look murky and green, but it also starts killing fish if the amount increases significantly.

This most certainly does not mean that you need to give up your hobby of keeping fish. You simply need to learn how best to manage algae by getting the right kind of fish.

We already know the answer to the question, do fish eat algae? Yes, they do. The question now is, what is algae? Why do they develop in a fish tank? Why get fish that eat algae? And why do you need to get rid of it in the first place?

Here are some simple to understand answers for you.

What is Algae?

Algae are technically speaking, plants. Everything that does not come under the root term of mosses or higher plants are referred to as algae. These include microscopic unicellular organisms, thread-like forms, along with macroscopic algae, like seaweeds. Some of them can grow to as large as 60 meters.

For life as we know it on Earth, algae are essential. They seem like a nuisance to you as the fish pet owner, but without them, the habitat of your wish will never be complete.

Algae Eating Fish For Aquarium (Video)


Can a Fish Tank be Algae Free?

100% free? No, it is literally impossible to have the tank absolutely algae free, because there are unicellular algae in air as well. You can be the neatest freak on earth, yet you cannot make your fish’s tank algae free. As per experts, you shouldn’t even try.

Biofilms are present in all aquariums, and they are extremely important for the well being of your fish. They contain unicellular algae along with many other microorganisms. These things ensure that the biological flora and fauna of the tank is balanced.

Why do Algae Form?

It is the first few weeks of the aquarium or tank, that algae is formed. This happens because the tank is being prepared for an ecological balance so that the fish can survive easily like it does in its natural habitat.

You as the aquarist will have to watch and wait for this new life to flourish. This is most definitely the right time to introduce fish eating algae in the tank, as they will make sure your tank has just the right amount of algae living in there. It is highly recommended that you have some fast-growing stem plants in the aquarium as that will help in creating the balance needed between the fish, plants, and algae.

Now that you know that algae cannot be gotten rid of completely, the best way to manage this situation is to opt for prevention. This is easily possible through the addition of algae eaters in the tank. These fish will ensure that your algae problem does not get out of hand.

But before you rush out the door to get algae eaters, you need to first find out which kind of algae infestation your tank has.

Here are the different types of algae that grow in aquariums and tanks:

  • Gold Slime: One of the most common types of algae is the gold slime. It looks, as the name suggests, like golden slime that is stuck to the glass and on other things in the tank. It occurs mostly in new aquariums and when the tank does not get enough light. The good news is this is readily eaten by fish and can also be wiped easily.
  • Green Slime: Another very common type of algae, green slime is mostly never seen because is eaten by many fish. You won’t even need to get a separate sit of algae eaters for this type of algae.
  • Green Water: One of the rarest kind of algae is the green water algae. But it is also the worst kind because no fish will eat it as it can be toxic for them. This makes it very hard to get rid of and most pet owners have to get rid of the entire tank to rid themselves of the infestation.
  • Thread Algae: Thread algae, also known as hair algae looks like thin wires or threads and are found floating in the tank. It grows fast and sticks to different surfaces as well.
  • Brush Algae: Looking like thick tufts of hair, brush algae sticks to plants and other things in the tank. It is happily chowed by algae eaters.
  • Green Dot Algae: Another common type of algae is the green dot algae, which appears in the form of dots on the aquarium glass and fixtures. Since it can multiply fast, it can completely coat the glass. This kind of algae does not end with the algae eating fish as most don’t eat it and the ones that do are unable to control its spread.
  • Blue/Green Algae: Blue or green algae is of the respective color and is commonly found in fish tanks. It is found floating in the water and is another algae that most fish refuse to eat as it is toxic.
  • Black Beard Algae: This algae is basically dark purple or black in color, and grows on aquarium plants. It can be eaten by algae eaters.

Now that you know about the basic algae that take place in the fish tank, you should know what kind of fish eat all these various kinds of algae.

Algae Eating Fish

The following fish are some of the best algae eaters that you will find. The one thing you will have to consider when investing in these fish is where you plan to keep them.

Are they for a fish tank, aquarium or do you have a pond filled with fish and algae? Once these questions are answered, it will be easier for you to decide which algae eating fish is the best one for you.

Here is a list that you can choose from.

1. Siamese Algae Eater

Siamese algae eaters come from freshwater carp family and are some of the most famous ones when it comes to consuming algae that grow in freshwater. Since these fish are not picky eaters, they will happily consume almost all kinds of algae that litter your tank or pond, from string algae to algae clumps, as well as the red algae.

These fish are rather sociable and can grow up to 6 inches, which means they are not well suited to live with small or docile fish like the minnows, guppies or small catfish. Instead, they fare better with koi and the common goldfish.

So long as you provide them with a warm temperature during the winter season, somewhere between 70-70 degrees F, they live a full life of up to 10 years.

2. Orocinclus Catfish

This is believed to be one of the best algae eaters in the market, particularly for small-scale pond owners and fish keepers. This is because these catfish are very small in size, no longer than 1-2 inches long, but have an appetite of a shark! They can devour huge amounts of algae in a short span of time, and any new growth is finished off faster than you can imagine.

As they are small and also very calm nature wise, they can be kept with pretty much all kinds of fish. They neither fight, nor create difficulty for other fish and exist peacefully.

Another great thing about these alga eaters is that even though they are ravenous eaters, they never harm the plants in your tank or pond. Yet, they still manage to find even the most hidden of algae in the nooks and canaries of an aquarium or pond.

Their small size is what makes them unsuitable for an excessively large pond where there are large fish that are carnivores. They will get eaten up without getting a chance to reduce the algae infestation.

They survive best in tropical climates as they need warm water temperatures, ones that fall within the bracket of 72-82 degrees F range.

3. Common Pleco

Do you live in a place that encourages the growth of algae? Well then, pleco is the best fish for your aquarium or pond. Why? Because just a single adult pleco can consume string algae in 1000 gallons of water. Keep in mind though that this would also depend on how much other food they are eating.

There are f course different varieties of pleco available. If you get a common pleco that is 1-2 feet long, it will automatically devour more algae as compared to the bristlenose pleco, which is only 4 inches long. You would have to choose depending on what size your tank or pond is. If you opt for a large common pleco, then opt for only 1 per 1000 gallons of water.

Since plecos are peace-loving and friendly fish, they can be kept with most other fish species. But according to experts, they fare best with their own kind.

Plecos are also a tropical fish that are originally from South America. This means they will have to be kept indoors for the winters if the temperature falls below 50°F.

4. Grass Carp

Grass Carp was actually brought to the US in the 1960s so that it could control the amount of weeds in various waterways. Originally from Asia, this fish could breed rapidly, which means that it grew in numbers very fast.

This perhaps is the reason why it is legal in some areas to have only the triploid grass carp, the variety which has an extra pair of chromosomes, which makes them infertile. Why do you need to know this? Because carp can become an invasive species pretty fast and can pretty much destroy the natural ecosystem outside of Asia. So you need to be very careful when getting this species of fish.

Grass Carp are perfect for problematic aquatic vegetation like duckweed. They also get rid of musk grass, a kind of green algae that is many times mistaken for a plant.

These are only suitable for large pounds as an adult Grass Carp weighs 55 pounds.

5. Pond Loach

Pond Loach, also known as weather loach or dojo loach, is another algae eater that is most suitable for rather cooler climates. They can easily survive in waters that have temperatures from 40 to 77 degrees F. They are perfect for new or beginner ponders or aquarists.

Since the pond loach can grow up to 1 foot, it is best that they are not kept in small tanks. They are also docile creatures that do well with other calm and peace-loving fish.

Compared to the plecos, the loaches don’t eat as much algae. This is because they also love to eat plant matter, food pallets, and insects.

What makes them so attractive is the fact that they can easily survive in cooler climates and people who don’t want the hassle of moving their fish inside once temperatures turn cool.

6. Twig catfish & Whiptail catfish

Twig catfish and whiptail catfish are two more great algae eaters that you can opt for. They are particularly well suited for tanks and small aquariums. the

Farlowella, as the twig catfish are called, get their name because of their twig-like shape. They are almost always found hiding among plants or stuck to the driftwood branches. They are also known as stick catfish. Growing up to 7 inches, this algae eater is just as efficient as the plecos. They can consume huge amounts of algae in a short span of time.

Whiptail catfish are flattened and stretched out like the plecos, often seeming like lizards. This is where they get the name lizard catfish. They too can devour algae-like plecos and this makes them a favorite among fish enthusiasts.

7. Flying fox

If it’s the soft slime algae that are worrying you, then flying fox is the perfect one for you. They are so pretty that they alone are enough in a tank. They look a lot like the Siamese algae eater, but with more colors and a temper to boot.

They are related to the red-tailed and rainbow sharks, which means that they are pretty territorial when it comes to living spaces. They work best with species of their own kind. Since they are small, a mere 6 inches, they cannot eat the bigger fish, but one per tank is more than enough.

8. Florida flagfish

The reason why they are in such demand is because they readily eat the brush or beard algae. This is the kind of algae that most algae eaters won’t touch. Problem is, the flagfish isn’t very friendly and though it grows to be only 2.5 inches, it can be aggressive towards its other tank mates. Therefore, you will need to be careful about who you board them with.

9. Stone-lapping fish

The stone-lapping fish is often confused with the flying fox and Siamese algae-eaters. They do resemble the flying fish, but their colors are more muted, there is no stripe on their tail and they have heavier bodies. The stone-lapping fish feeds on soft slime algae.

10. Livebearers

This isn’t one single fish but a variety of species, like the platies, mollies and guppies, known as the livebearers. They love only the soft hair algae or the strand algae, but will not eat any other kind. The algae is not their main source of food, which is why they are best if you want pet fish that will also clear the small amount of algae present in your tank.

The great thing about livebearers is that they are easy t raise, breed quickly and are friendly. This makes them ideal companions for other docile fish. Their size is also small, which makes them the perfect fit for a small aquarium or tank.

You will have to provide a warm climate to their tank or bring them in an inside tank once the temperatures drop. Mollies prefer 75 degrees while the guppies work best in 55 degrees F.

What’s more, the livebearers not only consume the algae, they also get rid of mosquito larvae and other insects.

11. Guppies & Koi

Guppies and Koi are another common pond pets that easily eat some kinds of algae. But like the livebearers, that is not the main source of their food. They prefer to have other food sources like food pellets and pond insects.

This means that even though they make for good pets or pond residents, you may still need other algae eaters for the actual algae infestation. This is why plecos are the perfect companion for koi and larger goldfish.

Don’t keep them with the smaller variety of goldfish, as they can latch onto them and ruin their scales. They also slime up the habitat if space is restricted.

12. Chinese High-Fin Banded Shark

Sounds unbelievable? Well, sharks also eat algae, even if the only similarity to a shark is a shared name! The Chinese high-fin banded shark actually looks more like a suckering algae eater, rather than an actual shark.

It is also known as the freshwater batfish and since it is a bottom feeder, algae is its main source of food. It has bold, banded colors, with a high dorsal fin. These are very pretty fish to have, even if they do grow quite long, about 4 feet. The good news is, they take quite a while to grow this large.

The batfish is another peace-loving fish, which can easily coexist with the goldfish, koi, guppies and many other fish species. But they still prefer their own kind.

These are another algae eater that prefer cool temperatures and can easily live in 55-75 degrees F. Keep in mind though that their size requires space for them and they cannot live in a small tank. This is what makes them the ideal algae eater for ponds and very large aquariums.

Frequently Asked Questions

Why do Algae grow too much in number?

The reason why algae become in an infestation is that you are not taking care of the maintenance of the tank. Have you been changing the water regularly? If not, then algae infestation is inevitable. 50% of the water should be changed at least once a week. The nutrients present in the water will remain and algae growth will be curtailed.

But water is not the only problem. If there is presence of strong light or lack of proper lighting, then too algae grow exponentially. Seasonal temperature changes can also lead to the sudden growth of algae in the fish tank. This is why algae eating fish are the best solution to your problem. But make sure you identify the kind of algae that exists in the tank and get relevant fish for it.

Is algae good for fish?

This depends on how you define good. Algae, if grown excessively, can become hazardous for fish that don’t eat it. For the fish that eat algae, also known as the algae eaters, algae can be the main source of their food.

This means that even if there is algae in your pond or fish tank, you can introduce algae eating fish in it and they could all survive well in that environment.

What kind of animals eat algae other than fish?

Fish eating algae are the only solution for algae infestation. If you want to introduce something more effective and suitable to your pond, then you can consider the following options:

  • Frogs: Frogs love algae. Of course, there is a certain kind that relies mostly on algae as food source and you will need to get that in order to get rid of an infestation.
  • Shrimps: There are many different types of shrimp that rely solely on algae as their food source. They are even better than some fish in getting rid of the algae infestation. Freshwater shrimp are some of the best cleanup crew that you can find. The ones you can introduce in your tank or pond include the Amano shrimp, the cherry shrimp, the ghost shrimp, and the bamboo shrimp.
  • Snails: Snails is another option that you can look into if you are thinking of getting rid of a huge amount of algae. Yes they can be a nuisance, but larger snails can also get rid of the algae problem pretty fast. Some guaranteed names include nerite snail, ramshorn snail, mystery apple snail, rabbit snail and the Malaysian trumpet snail.


So do fish eat algae? What are the best algae eating fish that you can find? The answer must now be simple to you. There are fish who eat algae and clean up a fish tank or pond for you. Some of the most common algae eaters are the plecos, the catfish, pond loach, flying fox, Siamese algae eater, and grass carp.

The most important thing you need to be aware of is the kind of algae that is infesting your pond or aquarium so that you can invest in the right kind of algae eater.

Once you know which algae eating fish is the best suited to your needs, you will be able to breed fish without any kind of algae problem.


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