5 Best Algae-Eating Fish for Small Aquariums

a school of siamese algae eaters.

As an aquascaper, I find it frustrating to see algae in my tanks. Whenever I see one, I take all the necessary steps to get rid of it. While algae are a natural part of freshwater aquariums, their overgrowth can turn a vibrant aquatic haven into a murky mess. Preventing or controlling algae is hard, especially when dealing with small tanks. A small tank is typically considered to be between 5 and 20 gallons in size. They are more susceptible to algae growth because they have less water volume. This means that any changes in water quality or nutrient levels can happen more quickly and easily, which can create ideal conditions for algae growth.

Thankfully, there is a group of unsung heroes in the fishkeeping world: algae-eating fish. These diligent underwater cleaners can transform your aquarium into a thriving ecosystem. By understanding the benefits of these fish, you will not only keep your tank aesthetically pleasing but also create a healthier environment for your aquatic companions.

Best Algae-Eating Fish for Your Small Tank

If you have a small tank, you might want to consider adding some algae-eating fish suited for it. These fish can help you reduce algae in your aquarium by feeding on it. They can also improve the water quality and appearance of your tank. There are a variety of algae-eating fish to choose from. Some of the most common ones are:

1. Siamese algae eater

a group of siamese algae eaters
Siamese Algae Eaters are often confused with Chinese Algae Eaters, which are much more aggressive and can grow up to twice their size. Photo: Janet Cremetti, Flickr

The Siamese algae eater is a popular freshwater fish that is known for its algae-eating abilities. It is a slender fish with a brown body and a black stripe running along its length. It grows to be about 6 inches long.

SAEs are not picky eaters and will eat a variety of algae, including green algae, brown algae, and black beard algae. They will also eat some plant matter and fish flakes. Additionally, they are known to eat more algae as juveniles than adults. As adults, they may compete with other fish for food and prefer the more palatable fish flakes and pellets to algae. Therefore, you may need to reduce food portion sizes to encourage older SAEs to eat algae again.

Keep in mind that this fish can be territorial with their own or similar-looking species, so it is best to keep them in groups of at least 3.

2. Otocinclus Catfish

Oto on the tank wall grazing algae.
Otocinclus catfish are social creatures and prefer to be in groups of at least 3 to 6. Photo: yuyu green

Otocinclus catfish, also known as dwarf suckers or otos, are small, peaceful catfish native to South America. They are popular aquarium fish due to their cute appearance, calm temperament, and algae-eating abilities. They are hardy and can thrive in nano tanks, making them one of the best algae eaters for small aquariums.

Otos will primarily eat soft algae, such as green algae and brown diatoms. They will also eat biofilm, which is a thin layer of microorganisms that grows on surfaces in the aquarium. However, Otocinclus catfish are not as effective at eating harder algae, such as black beard algae or green spot algae. Additionally, they are adept at cleaning the leaves of live plants without causing harm. To learn more about caring for these charming catfish, please read our full article.

3. American Flagfish

American flagfish on a tank
Jordanella floridae can thrive in cooler water temperatures, making them a good choice for unheated aquariums. Photo: vabbley, Flickr

The American flagfish (Jordanella floridae) is a colorful and hardy fish native to Florida. It is a member of the killifish family and gets its name from the resemblance of its pattern to the American flag.

These critters are omnivores and will eat a variety of algae, including green algae, brown algae, and black beard algae. They will also eat small insects and crustaceans. Furthermore, they are active and playful fish that enjoy swimming around and interacting with other fish. They are not aggressive and will not bother other fish in the tank.

American flagfish are hardy fish that can thrive in cooler water temperatures, making them a good choice for unheated aquariums. If you are looking for an algae eater for an unheated tank with fast-swimming tankmates, the American flagfish may be a good option.

4. Reticulated Hillstream Loach

A reticulated hillstream loach in a tank
With its striking stripes and flattened body, Sewellia lineolata is a fish that seems out of this world. Photo: Korkeasaaren eläintarha, Flicker

Reticulated hillstream loach (Sewellia lineolata) is a small, bottom-dwelling fish that is native to fast-flowing streams and rivers in Southeast Asia. They are known for their ability to cling to rocks and other surfaces in strong currents, and they are also voracious algae eaters. Although this fish resembles a catfish, it is actually a loach. It is a hardy loach species that can adapt to various freshwater environments. It has a special ventral fin that helps it cling to different surfaces in the aquarium, such as glass, plants, driftwood, and rocks, while it grazes on algae.

This fish feeds on algae and likes to clean near filters, air stones, and other sources of water flow. It will remove any growths from your aquarium walls, rocks, driftwood, and plant leaves, such as diatom algae, hair algae, and sometimes black beard algae.

As cute as it may seem, this fish can be territorial and defensive, even towards its own kind. Therefore, you should keep them in small numbers, ideally three loaches for a 25-gallon tank.

5. Panda Garra

Panda Garra in an aquarium
Say hello to the panda garra, a cute and friendly fish that can brighten up any tank. Don’t you just love their panda-like markings? Photo: Ted Perkins

Panda Garra (Garra flavatra) is a unique tropical fish that is native to Myanmar. It is known for its distinctive black and white striped pattern, which resembles a panda. Panda Garras are small fish, reaching only about 2.8 to 3.5 inches in length. They are peaceful and can be kept in community tanks with other small, non-aggressive fish.

This fish is easy to care for and adaptable to different aquarium setups. It is an omnivore that feeds on algae, biofilm, small insects, and more. It loves algae and can even eat black beard algae. This critter is also peaceful and compatible with many other fish, especially nano fish like tetras, danios, and rasboras.

Which is the Best algae eater for Your TANK?

The fish in the list above are some of the best algae-eating fish suitable for nano tanks. However, there is no one-size-fits-all answer to the question of which algae eater is best for your tank. The best algae eater for your tank will depend on the specific factors of your tank, such as the type of algae you have, the size and conditions of your tank, and any other tank inhabitants you may already have.

Do not use the wrong type of algae eater, or algae will continue to grow and flourish. The unwanted growth of algae does not rely solely on the effectiveness of algae eaters. Certain conditions, such as poor water quality, excessive lighting, and poor water movement, can also contribute to algae growth.

By addressing these factors and adding the right algae eaters, you can expect a clean, healthy, and algae-free tank. Happy fishkeeping!

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