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Siamese Algae Eater: Care Guide, Varieties, Lifespan & More

Lindsey Stanton Profile Picture

By Lindsey Stanton

Siamese algae eater

With so many different varieties of algae eaters, it can be difficult to choose which algae eater is best for you. Algae eaters help aquarists to keep their aquarium tidy and free of unsightly algae. There are a variety of algae eaters on the market and one for every tank’s size and requirements. Siamese algae eaters are active, fast-moving fish that will eat anything added into the tank. Algae eaters are described as the ‘vacuum cleaners’ of the tank. Although they do not consume waste leftover by themselves and other tankmates, they are excellent at cleaning up the substrate and decorations in the tank. Let’s learn more about adding Siamese algae eaters to your tank.

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Quick Facts About Siamese Algae Eater

Species Name: Crossocheilus oblongus
Family: Cyprinid
Care Level: Easy
Temperature: Tropical (24°C to 28°C)
Temperament: Peaceful, social
Color Form: Black stripes, gold, grey
Lifespan: 8 to 10 years
Size: 6 inches
Diet: Omnivore
Minimum Tank Size: 25 gallons
Tank Set-Up: Freshwater, planted
Compatibility: Community tanks

Siamese Algae Eater Overview

Image Credit: To Be Determined, Shutterstock

The Siamese algae eater, scientifically known as the Crossocheilus oblongs, is a freshwater tropical fish that falls into the family of cyprinid. Siamese algae eaters are related to a form of carp. Siamese algae eaters originate from Southeast Asia which includes Thailand and Malaysia. Siamese algae eaters are one of the best and most popular forms of algae eater in the aquarium industry. They are now bred widely across the world for sales within the aquarium trade. They cover a large space around the tank in a short amount of time, making them effective in rapidly cleaning up the aquarium. Their movements keep the tank full of activity and bring out the liveliness within an aquarium.

Compared to other species of algae eaters such as Plecos and Nerite snails, the Siamese are exceptionally more active and social. They are easy to acquire and rarely have behavioral issues that affect the balance within the aquarium. Siamese algae eaters make excellent cleaners for novice aquarists due to their hardy nature. The only downside to Siamese algae eaters is that they produce a high amount of waste. Although this is common for every algae eater, due to their small size compared to other algae eaters, they produce significantly less waste.

How Much Do Siamese Algae Eaters Cost?

Siamese algae eaters are fairly priced at pet stores and online. They are sold according to their size, color, and health which will cause the price to vary. Due to their popularity, nearly every pet store sells Siamese algae eaters and is considered cheap when compared to other algae eaters. If you decide to purchase the Siamese algae eater online, you will have to pay the additional costs of shipping and one to three days’ quick arrival as they are livestock. Once you have purchased your Siamese algae eater, it is essential to quarantine them for a one- to two-week period. This allows any illnesses to surface without it affecting the other fish in the tank.

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Typical Behavior & Temperament

Siamese algae eaters are peaceful community fish who mind their business amongst tankmates in the aquarium. They will actively swim around till they find a source of food such as algae to which they will hang around that spot and consume the algae. Once they have cleaned up the algae, they will swim off in search of other algae-targeted spots. Siamese algae eaters spend most of their time at the bottom of the aquarium, gliding across the substrate along with decorations, and on the inside of the glass. They are social within their species and can be observed forming small groups. Siamese algae eaters are hardly aggressive and do not attack or harm mid to top-dwelling fish with a peaceful temperament.

Image Credit: Swapan Photography, Shutterstock

Appearance & Varieties

Siamese algae eaters have slim bodies with narrow figures. They are not the most attractive or brightly colored fish and have a typical color form of pale grey or gold with black stripes. The black stripe is lined from the head down to the fish’s tails. They only reach a maximum size of 6 inches which is good for smaller tanks that cannot house larger algae eaters such as the Plecostomus. As the fish develops and matures, their once prominent black stripe may fade. The contrast of the black line alongside their size can be an indication of their age. Although, the change of color can be triggered by breeding behavior, stress, or dietary changes.

It is a difficult task to determine the gender of the Siamese algae eater until they are at least 4 inches in size. A telltale sign of gender difference is that females are significantly rounder and larger than males. Once the Siamese algae eater is over 3 years old, the mature size is reached, and female and male characteristics are easily distinguishable. The females will have a rounder abdomen to hold and deposit their eggs whereas males are narrow and have more prominent and pointed fins.

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How to Take Care of Siamese Algae Eaters

Habitat, Tank Conditions & Setup

Tank/aquarium size

Due to the average adult size of the Siamese algae eater being 6 inches, they require a minimum tank size of 25 gallons. This allows them to have enough space to encourage their activeness and comfortability. The ideal size for adult Siamese algae eaters is 55 gallons. The tank should be rectangular and Siamese algae eaters should not be housed in spherical aquariums. This will affect how they see the outside world and will deter them from cleaning the glass. Most bowls are too small to appropriately house a Siamese algae eater. They make poor nano tank fish and suffer in cramped conditions.

Water temperature and pH

The aquarium should be tropical with a preset heater, with a stable temperature range between 24°C and 28°C. Their activity level depends on the temperature of the water. Ideally, the pH should be between 6.5 to 7.0. Although they can tolerate a pH of 6.0 to 7.5. The overall water hardness should be between 5 to 20 dH.


Siamese algae eaters are bottom-dwellers and require a substrate that will not scrape up their underside. Smooth pebbles and aquarium sand is ideal for Siamese algae eaters. Bare bottom tanks are doable, but the substrate is encouraged as it hosts beneficial bacteria that are essential for the health of the aquarium.


Siamese algae eaters thrive in heavily planted tanks. They appreciate plants like anubias, hornwort, and amazon swords. Adding other natural decorations like logs and aquarium stones and rocks provide the coverage they need to feel sheltered.


Siamese algae eaters are easily disturbed by bright lights coming from windows or artificial lights. If the tank is brightly lit, you may notice a decrease in their activity and find them hiding underneath leaves or decorations.


Due to the high bioload Siamese algae eaters produce, they require a strongly filtered tank. They require a filter that can intake five times the amount of water volume in a minute. They do poorly with strong currents and the filter should produce more aeration than current.

Image Credit: Grigorev Mikhail, Shutterstock

Are Siamese Algae Eaters Good Tank Mates?

Siamese algae eaters make good community tank mates both to other fish and their species. Housing your Siamese algae eater with other peaceful fish is the best option to obtain a tranquil aquarium. Siamese algae eaters are active yet peaceful creatures and there is a variety of suitable tankmates. Due to Siamese algae eaters spending most of their time at the bottom of the aquarium, you must avoid keeping other algae-eating species of fish alongside your Siamese algae eater. This may cause competition and stress amongst the two species. Some fish such as the bottom-dwelling red-tailed shark will become territorial and chase your Siamese algae eater, leading to stress and eventually illness due to a weak immune system lowered by stress.

Corydoras can tolerate your Siamese algae eater given the tank is large enough to house both comfortably. Cramped conditions will cause your Siamese algae eater to be preyed on by fin nippers or chasers. By choosing fish that swim at different layers of the tank, you have a wide selection of good tankmates for your Siamese algae eater. The territorial cichlid fish should be avoided at all costs.

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What to Feed Your Siamese Algae Eater

As their name suggests, Siamese algae eaters primarily consume various types of algae. They are omnivores but lean towards being more omnivorous in captivity due to processed foods containing a higher amount of protein than they will eat in the wild. In nature, they will rarely consume dead fish and insects but take a preference to consume algae and live or rotting plant matter.

Due to Siamese algae eaters being scavengers, they will eat what they find at the bottom of the aquarium. They are not fussy when it comes to food in captivity and will accept processed foods sold in pet stores. This includes sinking flakes, granules, pellets, or algae wafers. It is ideal to leave a few patches of algae to grow within the tank, so they have a constant source of food to graze on. Sprinkling the food around the tank encourages their natural foraging behavior which in turn keeps them preoccupied throughout the day.

Siamese algae eaters will also willingly eat live foods such as brine shrimp, daphnia, bloodworms, and tubifex worms. Over-feeding is a common problem with algae eaters as they will already have access to food in the aquarium in the form of algae and plants. It is important to ensure the stomach of your Siamese algae eater is not abnormally swollen.

Keeping Your Siamese Algae Eater Healthy

Siamese algae eaters are not particularly prone to many illnesses and are easy to keep healthy. Following their basic requirements and tank conditions will keep them in good health with a strong immune system. Preventing disease is more effective than treating the disease.

  • Only add appropriate decorations and gravel that will not scrape them into the aquarium. There should be no small opening they can get stuck in, or any decorations and colored gravel that leaks toxins. When toxic and cheap artificial decorations are kept in a tropical aquarium, the toxins release themselves significantly faster.
  • Water renewal should be a frequent practice. Water changes should be done when the water parameters start to spike. All fish require clean and filtered water within their aquarium. Clean water is the best defense against external infections and disease.
  • Siamese algae eaters require quality foods and cannot only eat algae. They need food that contains their necessary minerals and vitamins. The food should contain little to no cheap fillers. This could mean you will have to pay more for a portion of better-quality food.


Although Siamese algae eaters mate in the same way as many other fish, you will find it difficult to breed these fish in your home aquarium. In Siamese algae eater breeding farms, hormones are used to encourage breeding, something which many aquarists are unable to do. Sexing the Siamese algae eater is difficult enough, so choosing a compatible breeding pair is not an easy task. In the wild, spawning is triggered by a temperature and pH change.

Little is known about successfully breeding these fish in captivity and should not be messed with by novice aquarists. Changing the temperature and pH in the water is a diligent task that can upset the fish if not done properly. Sudden changes in the water chemistry will upset even the hardy fish species.

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Are Siamese Algae Eaters Suitable For Your Aquarium?

If you are looking for a peaceful and small growing algae eater that is good for both beginner and advanced aquarists, a Siamese algae eater may be a good option. If you keep a fully cycled tropical aquarium above 25 gallons with peaceful tankmates, the Siamese algae eater will fit right in! Stubborn algae problems can be solved by purchasing a small group of Siamese algae eaters that will consume the algae in a matter of minutes. They will prevent algae outbreaks and keep your tank looking clean and neatly maintained. We hope this article has helped you decide if a Siamese algae eater is the right fish for you.

Check out some of our other tank life species care guides:

Featured Image Credit: Grigorev Mikhail, Shutterstock

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