Siamese Algae Eater: Care, Breeding, Diet & Behavior

Siamese Algae Eater Complete Guide

Siamese Algae Eaters do just what the name suggests: They are excellent and efficient algae eaters that help keep an aquarium clean.

Siamese Algae Eaters are freshwater fish in the carp family. They are native to Southeast Asia, found in the Mekong and Chao Phraya basins and the Malay Peninsula, living in freshwater streams and rivers, and are algae-eating bottom dwellers.

They are low maintenance and peaceful fish, so they are an excellent choice for beginning aquarists and a great tankmate for a wide range of other fish.

While the Siamese Algae Eater is not especially colorful, they are active fish and will school together. So, they offer more visual interest than slow-moving algae eaters like snails.

Siamese Algae Eater Size and Appearance

Several fish species look very similar to the Siamese Algae Eater and may be mislabeled. For clarification, here is an overview of Siamese Algae Eater species.

Siamese Algae Eater

Crossocheilus siamensis, Crossocheilus oblongus, and crossocheilus varities

These are often called the “true” Siamese Algae Eaters and are the most desirable species for ordinary fish tanks. To identify this fish, look for:

  • A dorsal fin with no pigment
  • A single black stripe down the side, with no gold band above it
  • A “jagged,” toothed edge on the black stripe

Siamese Algae EaterGyrinocheilus aymonieri

Also called the “Chinese Algae Eater,” this large fish is a popular food source and unlikely to be mistaken for a Crossocheilus, despite the identical common name.

Flying Fox Epalzeorhynchos kalopterus

The Flying Fox looks very similar to a Siamese Algae Eater, and the two species are often confused in the aquarium trade. To identify a Flying Fox, look for:

  • Dark bands or coloration in their dorsal and lower fins
  • A gold or light band above the black stripe on their side
  • A smooth edge on their black stripe

False Siamese Algae Eater – Garra cambodgiensis

The Cambodian logsucker is another algae eater that looks virtually identical to the Siamese Algae Eater. To identify this fish, look for:

  • A black or dark dorsal stripe along their backs
  • The side stripe is wider than in Crossocheilus and smooth at the edges
  • The black dorsal stripe and black side stripe create a light side stripe between them on the sides of the fish

Both Flying Foxes and False Siamese Algae Eaters may have hints of color like yellow or orange, which a Siamese Algae Eater does not, and they also have twin barbells.

In contrast, the true Siamese Algae Eater has only one (although this detail may be hard to see in these small, active fish).

Correct identification is essential because the true Siamese Algae Eater is a mellow fish that best thrives in a small school. Flying Foxes and False Siamese Algae Eaters are solitary fish that may become aggressive to other fish of their species.

The true Siamese Algae Eater is a pale grey or silver freshwater fish with a dark or black stripe down their sides from head to tail. They have a long, narrow body and reach up to six inches in length.

Habitat and Tank Conditions for Siamese Algae Eater

Siamese Algae Eaters spend most of their time near the bottom of slow-moving, densely planted rivers and streams.

They require lots of plants and small caves for shelter and hiding places and need a soft substrate that won’t scratch the bottom of their bodies.

They tend to stay near sheltered spots and seldom swim to the water’s surface. But, they are also active fish that have been known to jump, so they require an aquarium with a lid.

Siamese Algae Eaters do not have the “swim bladder” that most fish have and have to keep moving, or they sink to the bottom.

Because they cannot rest in the water, they like to have rocks or décor to rest on. It is also essential to create small caves and hiding places at the bottom of the tank where they can rest, hide, and be alone without having to swim.

Siamese Algae Eaters can be kept alone but do best in a small school of 4-6 individuals.

Food and Diet Information

As you may have guessed, Siamese Algae Eaters eat algae, vegetation, and decomposing plants. However, they are omnivores and scavengers and will eat protein when they can find it. They are not fussy eaters and have a tendency to overeat.

They will eat flake and pellet foods, live foods, algae wafers, and more. Siamese Algae Eaters may prefer prepared foods and stop eating tank algae, especially if they are overfed. Feed them once a day, and limit food to the amount they can finish in a couple of minutes.

Siamese Algae Eaters may nibble on plants when they are hungry, so it’s a good idea to keep a fast-growing plant species in your tank with them.

Siamese Algae Eater

Ideal Tank Size and Water Conditions

Siamese Algae Eaters need at least a 20-gallon tank. A good rule is to have 20 gallons for your first fish and 10 additional gallons for every Siamese Algae Eater after that.

Water Conditions

  • Temperature: 75-79°F
  • Hardness: 5-20 dH
  • pH: 6.5-7.0

Behavior and Temperament

Siamese Algae Eaters are peaceful fish and will get along with a wide range of tank mates. They are also relatively tolerant of diverse water conditions and not prone to disease.

While Siamese Algae Eaters are social and do best in small schools, it’s essential to avoid overpopulation for your tank size.

Like any fish, Siamese Algae Eaters create waste and ammonia, and having too many will eventually generate more tank dirt and debris than the fish consume.

Siamese Algae Eaters are a great mix of active and social while being mellow and calm. They are active swimmers but will also seek out quiet places to rest and hide.

They move quickly from algae patch to patch, actively scavenging and investigating the bottom of a tank. This activity and motion can sometimes be distressing for other aquarium inhabitants who prefer a calmer environment.


It is difficult for home aquarists to breed Siamese Algae Eaters. It is virtually impossible to distinguish males from females until they are 3-4 years old when the females’ larger size becomes apparent.

Because breeding appears to be dependent on the presence of certain hormones, and we aren’t exactly sure what triggers spawning in this species, they are only successfully bred in professional fish farm environments.