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Siamese Algae Eater PDF Print E-mail
Written by Aziz Dhanani   

Prior to converting my 40 gallon unplanted aquarium to a 40 gallon planted aquarium, I had a real Siamese algae eater (Crossocheilus siamensis)  that was a long time (8 years) inhabitant.  He was a solitary resident who kept to himself, was not aggressive towards any of the other inhabitants, and had grown to about 6 inches in length.  I even named him Nessie (after the fabled Loch Ness Monster).  I still remember how my family and friends were in awe of Nessie owing to his size. 

 Siamese Algae Eaters Profile 

Sadly things took a turn for the worse for Nessie.  This was due to the fact that I turned up CO2 levels too high.  As soon as I realized my mistake, I tried pumping the aquarium with oxygen, but it was too late for Nessie.  He never recovered. 

A major algae bloom also engulfed my aquarium as I did not coordinate lighting, CO2 injection, and fertilization in a way that would have prevented this.  To give you an idea of what my aquarium looked like.  This is a picture of the aquarium a few days after I converted it to a planted tank.Algae Growing Before SAE

The different types of algae that plagued the tank included: Black beard/black brush algae, green dust algae, and green thread algae.  Frequent water changes (two to three times a  week), overdosing Seachem Excel (three times the daily dosage), and a reduced lighting period, all but eradicated the algae, with the exception of the black beard/brush algae.  In my desperate attempts to try and eradicate this algae, I decided to add an Albino Bristlenose Plecostomus  and Siamese Algae Eater.  I watched in utter amazement as this dynamic duo grazed on the black brush/black beard algae.  It was  like watching cattle grazing madly at field grass.  They literally eradicated the algae in less then a week.

This is the same tank 3 months after the algae breakout and action taken to eradicate the algae, including the introduction of the “dynamic duo.”

3 Months After Introduction of SAE 

The Siamese Algae Eater Really Eats Algae!

It is not uncommon for people new to planted tanks and even experienced individuals to struggle with black beard/brush algae, not to mention the dreaded red algae.  Although I am not suggesting that algae eaters be solely used to control or eliminate algae without addressing the underlying causes,  the Siamese Algae eater (SAE) may prove a helpful ally for anyone faced with the daunting task of battling a black brush/beard algae bloom.   Interestingly, it first garnered interest in the 1970's when it was observed eating red brush algae.   It is even said by sources from Badman’s Tropical Fish Site that  “..the SAE, when coupled with the Amano shrimp (Caridina japonica), can deliver a knockout punch to any algae-ridden tank!”

Origins of the SAE

The real Siamese Algae Eater (not to be confused with the Chinese Algae Eater) is found in densely planted streams and rivers and even flooded forests in  South East Asia, including Thailand and the Malay peninsula.  Females are said to appear fuller/fatter than the males.  This often is the sole factor used to distinguish males from females.  The  real Siamese algae eater is said to reach a maximum size of six inches and have a life span of approximately ten years.  It has not been successfully bred in captivity.  All specimens purchased from pet stores have allegedly been captured from the wild and imported.  The Siamese algae eater is only suitable for tanks for 20 gallons as it will easily grow to six inches.


With respect to compatibility,  the real Siamese's algae eater is said to be compatible with most fish. However, the real Siamese algae eater should not be kept with the red tailed shark.  The red tailed shark is related to the Siamese algae eater and this fact is known to bring out the territorial and hence aggressive tendencies of both fish.   Having more than one real Siamese algae eater in the same tank is also not recommended as males are known to behave aggressively towards one another in staking out territory.  

Also,  the real Siamese algae eater not be kept with some fish that are spawning such as dwarf cichlids.   Siamese algae eaters are highly active fish. Their activity could potentially stress out fish that are spawning. 

I have seen my Siamese algae eater chase my black skirt tetras  when the black skirt tetras invade his territory and attempt to feed off the algae eater's  piece of zucchini.  Ironically,  the black skirt tetras often harassed my Siamese algae eater when I first purchased him. At that time, he was considerably smaller than the black skirt tetras.  I still remember how they would nip at  his tail constantly as he would try and eat at the algae caked on the glass. 

Although there is no scientific evidence of this, there is a possibility that smaller fish that share the body color may bring out the Siamese algae eater's aggression.  I have yet to see my Siamese algae chase any of my other fish that are the same size or larger with different color and body markings.   In fact, I have seen these fish freely venture into the Siamese algae's territory and even feed off the zucchini left for the Siamese algae eater.  In such cases, my Siamese algae eater will often leave the area or return when the other fish leave.

The real Siamese algae eater is not destructive towards aquarium plants.

Care RequirementsA Flying Fox

They  prefer a temperature of 21-29 degrees Celsius, a ph of 6.2-8.0, 5-20 dh water hardness.  A soft water current and a densely planted aquarium is recommended to try and mimic its natural habitat.   It is really important to keep them in a covered aquarium as they are known aquarium jumpers.  I have a custom made aquarium and since the tank cover accidently cracked I was unable to replace it.  I have been resorting to maintaining a dense mass of floating plants.  This has effectively served to keep my Siamese algae eater from jumping out. 

As far as feeding goes, the real Siamese algae eater has no special requirements.  They are known to accept normal fish food, algae disks, and blanched zucchini.   Overfeeding these fish allegedly causes them to become lazy and develop a preference for flake food over algae.  If you have a heavy black beard/brush algae infestation, you should feed these fish as little as possible to entice them to feed off the black beard/brush algae.  

The Siamese algae eater is even said to eat planarian worms, making them ideal additions to any tank infested with such worms. 

My real Siamese algae eater loves feeding off zucchini that has been microwaved for 60-80 seconds.  Once a week he enjoys a special treat of frozen blood worms.  Below is  a picture of my real Siamese algae eater enjoying some zucchini.  As you can see, he has no problems sharing with my Albino Bristlenose Pleco.

Slow Acclimation

Equally important is ensuring that your tank is properly cycled and that you properly acclimatize the fish prior to adding him or her to your tank.  I find that the drip acclimatization method works best for me. When acclimatizing any fish to a new tank, slowly introduce small amounts of new tank water to a large bowl where your fish is waiting in its original water.

Get a “Real” Siamese Algae Eater

The most important thing for anyone who is considering purchasing this fish is ensuring that you purchase a “real” Siamese algae eater (Crossocheilus siamensis) vs. a flying fox (Epalzeorhynchos kalopteru), "false” Siamese algae eater (Epalzeorhynchos sp. or Garra taeniata), or Chinese algae eater (Gyrinocheilus aymonieri).  This is particularly important if you are looking at getting this fish to help clean up algae.  Only the “real” Siamese algae eater is known to consume thread algae, black beard algae, and black brush algae.   

In my experience, it is not uncommon to find pet store staff and owners who are unable to distinguish these fish.  I have had fish store clerk try and convince me that the flying fox and “real” Siamese algae eater were  one in the same.  Confusion also abounds as you may come across literature that mistakenly fails to provide a clear distinction between these different species.

When I hear aquarium fish keepers say how horrible, terrible, and aggressive the Siamese algae eater is and how they would never consider purchasing another since they have never observed them eating any algae,  I often wonder if they have not mistakenly purchased a Chinese algae eater believing it to be a “real” Siamese algae eater.  Apart from that, it is possible that the odd “real” algae eater may turn out to be more aggressive than normal. It is not uncommon for fish of the same species to behave differently with all other things being equal.  This is not particular to Siamese algae eaters.  This may be in large part be due to innate differences in personality or temperament.

The major distinguishing characteristics that set the “real” Siamese's algae eater apart from the other algae eaters is the more intense black and white contrast, transparent  fins, and a black zig- zagged horizontal stripe which extends all the way down the tip of the tail.   Since it is so easy to get fooled or be fooled into purchasing fish that may not be “real” Siamese algae eaters,

I strongly urge readers who are considering purchasing a “real”  Siamese algae eater to refer to the different SAE Guides (below) on the internet as a reference to ensure that you purchase the right fish. 



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