Siamese Algae Eater Care – Tank Requirements, Fish Pairing, Diet, etc.

Siamese Algae Eater Care – Tank Requirements, Fish Pairing, Diet, etc.

Species Summary

The siamese algae eater, Latin name Crossocheilus oblongus, is a small freshwater fish belonging to the same family as Carp. They are of Southeast Asia origin, commonly found in Malaysia and Thailand. Unlike other algae eaters, they move around the tank quite a lot, so they make your tank more interesting and active.

As well as being a small and attractive looking fish, algae eaters are also hard workers. They help to keep your tank clean by grazing on algae growth.


Due to their popularity and ease of care, they are readily available from most pet stores and aquarists. They are also very cheap, between $3 and $5 per individual. Most places will also offer a small discount when buying more than one.

Siamese Algae Eater Lifespan

Siamese algae eaters are a fish you will need to be committed to. They can live as long as 10 years if kept in a tank with the right temperature and pH. They are not sexually mature until 3 or 4 years old. It is at this point that identifying gender is possible.


They are easily confused with the Siamese flying fox since they look so similar. The easiest way to tell them apart is to check for flaps on the corner of the mouth. Siamese algae eaters do not have any flaps, whereas flying foxes do. you can also check where their black stripe ends. For flying foxes, the stripe stops where the tail fin begins, but Siamese algae eaters have stripes right to the end of their tail fins.

Siamese algae eaters can grow up to 6 inches. They have long, narrow bodies of pale grey or gold looking scales, with a thick black  strip down the entire length from head to tail.

Until the age of 3 or 4, males and females look exactly the same. In older fish, it is easier to tell the difference as females can be up to 30% larger than males.

Siamese Algae Eater Tank

For one Siamese algae eater you will need a tank size of at least 20 gallons. If you want to keep more than one, you will need to add 10 gallons for each additional Siamese algae eater. So, if you wish to keep 4 individuals together, you will need a 50-gallon tank or larger.

Since Siamese algae eaters are active swimmers, they are able to jump. Be sure to have a lid on your tank to prevent any escapes.


Sand is the best substrate as algae eaters spend most of their time at the bottom of the tank, so you want to avoid rough substrates that may cause injury.

You can use an aquarium soil instead of sand or a very fine gravel as an alternative. Pebbles larger than the algae eater’s mouth are also a good addition to the tank floor.

Plants and Decorations

siamese algae eater diet

You will need to provide a variety of shelters including plants, rocks and logs/driftwood. Siamese algae eaters tend to stay near familiar hides and very rarely venture to the water surface.

A variety of these decorations within the tank will provide optimum conditions for your algae eaters. A lack of places to hide can cause stress and abnormal behavior.

Good plants to choose are those with wide flat leaves. Siamese algae eaters will rest on these leaves when they are not scouring the tank for algae spots.

If your algae eaters do not get enough food, they may start eating other plants in the tank. To combat this, include fast growing plants like hornwot.

Siamese Algae Eater Tank Parameters

Siamese algae eaters need a temperature between 75 and 79°F, so you will need to get a tank heater.

The ideal tank size for siamese algae eaters is 20 gallons.

The ideal pH is 6.5-7, however, if you have other fish within the tank, Siamese algae eaters are capable of tolerating wider ranges between 6 and 8.

Since they are mostly bottom dwellers where the water flow would naturally be slow, they do not require any particular assistance here. A standard sponge filter will do fine for aeration.

Siamese Algae Eater Health

siamese algae eater tank

As with many hardy fish, most diseases and infections can be preventing by maintaining the correct water parameters and performing regular water changes.

Siamese algae eaters can get parasites known commonly as “ich”. This presents as small white dots on the body. A 20-30% water change daily will reduce nitrite build up and remove waste from the tank.

As you are doing daily water changes, you may also need to raise the tank temperature. A fluctuation of 30 degrees either way can leave your fish susceptible to diseases.

A salt bath in a quarantine tank will cure your Siamese algae eater. If more than one is infected, you can add the salt directly to the tank, but be mindful of other species in the tank and do regular water tests.

Siamese Algae Eater Food & Diet

Like their name suggests, algae is the main part of their diet. However, it is important to remember that they are scavengers, so anything that falls to the bottom of the tank will be eaten, including dead fish! You can feed them algae flakes, plus some live food to keep their diet varied. Brine shrimp and bloodworms are good options.

If they are fed too much food, they will stop feeding on algae, which can cause algae blooms in the tank. This will have a negative effect on the tank parameters, so be careful not to feed more than what they can eat in a few minutes. Feeding should be once per day.

Will They Eat Black Algae?

Take a look at the video posted below to learn more!

Behavior & Temperament

Siamese algae eaters are not aggressive and will form small groups if you keep multiple algae eaters together. They will also feed from the same algae spots. They are fine in groups of 4-6 but are also quite happy as a single fish or a pair.

Unlike other algae eaters that move slowly around the tank, Siamese algae eaters are quite active swimmers.

Aquarium Mates

siamese algae eater tank mates

Siamese algae eaters are the perfect fish for community tanks because they are not aggressive or territorial and spend most of their time at the bottom of the tank. Corydoras are a great group of bottom dwelling fish that will not harass your algae eaters.

Middle dwelling fish likes Danios, Tetras and Guppies are perfect as they are not territorial and rarely venture to the bottom of the tank. Larger placid fish like Barbs are also a safe choice.

Cherry shrimp and Nerite snails can also be kept safely in a tank with Siamese algae eaters. Remember not to add too many as you can easily overstock your tank.

Siamese Algae Eater FAQ

  1. Are Siamese algae eaters aggressive?

    No they are not aggressive or territorial. If you see aggressive behavior it is possible that you have been sold a Siamese flying fox, which are known to show aggression towards their tank mates.

  2. How big does a Siamese algae eater get?

    Adult Siamese algae eaters can grow to 6 inches.

  3. Can I keep one Siamese algae eater?

    Yes, a single Siamese algae eater will be fine. They do not need to be kept in a group.

  4. What eats a Siamese algae eater?

    Algae is their main food source, but they will eat pretty much anything you put in the tank.

  5. How do I know if my Siamese algae eater is real?

    They can be confused with Siamese flying foxes. A Siamese algae eater has a black stripe that goes all the way to the tip of their tail, whereas the flying fox stripe stops before the tail fin starts.

  6. Do Siamese algae eaters jump?

    Although they spend most of their time at the bottom of the tank, they are energetic swimmers and are capable of jumping. You will need to put a lid on your tank.

  7. Do Siamese algae eaters eat other fish?

    They are not aggressive, but if a fish dies and sinks to the bottom of the tank, Siamese algae eaters will eat them. They are scavengers after all.


Siamese algae eaters may not be the most colorful aquarium fish, but they are active and help to keep your tank clean. They are also low maintenance so they are a great fish for beginners.

They do need a fair bit of space though, so you will need to be mindful when choosing how many to keep together. The first Siamese algae eater will need a 20-gallon tank, but for each one you add after, you should add another 10 gallons. Although they breed in the same way as other fish, Siamese algae eaters do not breed in tanks. They have only been known to breed in fish farms with the addition of certain hormones.

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