Siamese Algae Eater: Fish Profile, Care & Diet

  • Species name: Crossocheilus siamensis or Crossocheilus oblongus
  • Common names: Siamese Algae Eater, SAE
  • Family: Cyprinidae
  • Order: Cyprinidae
  • Class: Cyprinids
  • Maximum length: 6.3″ (16cm) when fully grown
  • Minimum tank size: 30 gallons
  • Hardiness: Easy, but make sure there are algae for it to eat.
  • Aggressiveness: Semi-aggressive. Suitable for a community aquarium with other peaceful fish. It is territorial towards its own kind and should either be kept singly or in groups of 5 or more.
  • Distribution: Thailand, Malayan peninsula.
  • Diet: Omninvore. In the wild, the Siamese Algae Eaters feeds on algae, periphyton and phytoplankton. Will take any commercially available fish food, live food, meaty foods, algae wafers and catfish pellets. Will eat green hair algae. May ignore algae in favor to commercial food if given a diet too rich in protein.

Crossocheilus siamensis, also known as Siamese Algae Eater or simply SAE is a freshwater fish in the Cibrinidae family (carp family). Native to the Malayan peninsula, the Siamese Algae Eater is a bottom-dwelling fish that lives in streams and rivers as well as flooded forest where it feeds on algae, periphyton and phytoplankton.

The Siamese Algae Eater is a long slender fish with a brownish-beige body. It has a bold black strip (one on each side) running the full length of its body. The stripe also extends to the very edge of its caudal fin, which is almost clear otherwise. It has clear see through fins and Rostral‎ barbels (‘moustache’). Females are slightly broader in the mid-section when compared to slimmer males.

Siamese Algae Eaters do not have the swim bladder so the fish must be in constant motion of it sinks.

SAE Copycats: Flying Fox and False SAE

It is important to learn how to tell a true Siamese Algae Eater from the many imitations that are often sold: False SAE (Epalzeorhynchus sp.) and the Flying Fox (Epalzeorhynchus kalopterus).

The brown coloring on top of the False SAE is a bit darker than on the SAE. The black stripe has a bordering gold stripe on top and, most importantly, the black stripe does NOT extend into the tail fin. It stops at the base of the tail.

Fake SAE (Epalzeorhynchus sp.)

The Flying Fox has the same gold band bordering the top of the black band as with the false SAE. The fins have a yellow-to-orange tint to them. A true Siamese Algae Eater should have clear fins.

Algae Eating

The Siamese became popular for their appetite for algae. It is true that is a great moss eater but there is a limit to its appetite. You’ll still need to find the cause of your algae problem and fix it if you want to win the battle. The fish is just a good helper.

Black Algae

Siamese Algae Eaters (Crossocheilus oblongus) are known for their ability to eat black algae, also known as black beard algae or brush algae (scientifically called Audouinella or Rhodochorton). They are one of the few fish species that can effectively consume and help control this type of algae in an aquarium.

However, it’s essential to address the underlying issues causing black algae growth, such as poor water quality, excess nutrients, or inadequate lighting. Regular maintenance, including water changes, proper filtration, and balancing light exposure, can help prevent black algae from becoming a problem in the first place.

Keep in mind that Siamese Algae Eaters may not be able to eliminate a severe black algae infestation on their own. In such cases, manual removal, spot treatment with liquid carbon or hydrogen peroxide, and addressing the root causes of the algae growth are essential steps to take alongside the introduction of Siamese Algae Eaters.

Other algae

Unfortunately, the Siamese Algae Eater is not a cure for all algae: Green spot and blue green algae are not on the menu. Finally, the Siamese Eater will eat fewer algae as it gets older.

Water Conditions, pH & Temperature

The ideal aquarium for the Siamese Algae Eater should be well-oxygenated with a pH between 6.5 and 8.0, a dH of 5-20, and a water temperature of 24°C – 26°C.

Since they can’t stay in mid-water, they love driftwood/rocks and some plants that can support their weight to rest on. Amazon Sword plants are perfect for this fish. This fish can be shy so make sure to provide some hiding places.

Now you know how to care for your algae eater.

Are Siamese algae eaters schooling fish?

Siamese Algae Eaters (Crossocheilus oblongus) are not considered schooling fish in the traditional sense, as they don’t exhibit the tightly coordinated swimming patterns seen in true schooling fish. However, they are social and tend to be more comfortable when kept in small groups or with other similar species.

It is generally recommended to keep Siamese Algae Eaters in groups of at least 3-5 individuals, as this can help reduce stress and encourage more natural behavior. In a group, they may display some shoaling behavior, which is a looser form of social interaction where fish swim near each other but without the tight coordination seen in schooling fish. Providing enough hiding spaces and a large enough aquarium is also essential to minimize territorial disputes and ensure a harmonious environment for all your fish.

How many Siamese algae eaters should you keep together?

It is recommended to keep Siamese Algae Eaters in groups of at least 3-5 individuals. Keeping them in small groups allows them to exhibit more natural behavior and reduces stress, as they are more comfortable with others of their own species. This also helps in evenly distributing their algae-eating capabilities throughout the aquarium.

When keeping a group of Siamese Algae Eaters, make sure your aquarium is large enough to accommodate them, as they can grow up to 6 inches in length. A tank of at least 30 gallons is advisable for a small group, with larger tanks required if you plan to keep additional fish or a larger group of Siamese Algae Eaters. Also, provide plenty of hiding spaces and a variety of plants, driftwood, and rocks to create a comfortable environment for them to thrive.


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