Siamese algae eater: Size, care, breeding and tank mates

Siamese algae eater fill a particular role, they are perfect for someone looking for a fish that will help with clearing algae to clean their tank. 

Sometimes you may get lost in the amount of freshwater varieties there are when looking for fish to add to your tank, but other times you ‘re looking for a fish to fill a particular role. 

They are active and social creatures, both in large groups, and when kept alone, they will do well. They are easy at feeding time and will eat anything put in their tank. 

These fish are ideal for beginners, because they are peaceful, to add to their community aquarium. One thing to look out for is the Siamese flying fox, which looks almost identical with the algae eaters and is often confused as a consequence. 

This article will discuss everything you need to know about buying and eating Siamese algae, including their care, their size, what to feed them

The Siamese algae-eater (Crossocheilus oblongus) is a freshwater fish species within the carp family, Cyprinidae.

This bottom-dwelling tropical fish is found in the Southeast Asian mainland, including the basins of Chao Phraya and Mekong as well as the Malay Peninsula.

Its natural habitats, during the rainy season, are streams and rivers and flooded forests. The Siamese algae-eater should not be mistaken for the flying fox (Epalzeorhynchos kalopterus) or the false siamensis (Garra cambodgiensis), lacking the former ‘s distinctive black bands.


Here is the scientific classification of Siamese algae eater fish

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Subfamily: Labeoninae
Genus: Crossocheilus
C. oblongus
Binomial name
Crossocheilus oblongus


The Siamese algae-eater has a horizontal black stripe which extends from opercle to tail. The stripe can fade in order to camouflage the fish against their surroundings.

Genuine Crossocheilus siamensis is occasionally found in the aquarium trade, without maxillary barbels and with heavily fringed V-shaped upper lip.

Crossocheilus langei, a plant commonly sold as the Siamese algae-eater, is closely related. It has a bright elongated brownish body, with a slightly flat belly. It has a prominent horizontal brown-black stripe which extends from nose to tail.

This fish can grow up to 16 centimeters (6.3 in.) in length. It has thin maxillary barbels, and a shallowly arcuate upper lip that is unfringed.

Two other related species, namely Crossocheilus atrilimes, a species that prefers Java moss to red algae, and an undescribed species of Crossocheilus, are traded as Siamese algae eater.

This family also includes carp which is closely related. They originated in Southeast Asia, including Thailand and Malaysia, but are now being bred for the aquarium trade worldwide.

The reason they have become so popular is because they are one of the best algae eaters on offer. They move around a lot, so they quickly cover the entire tank. 

Although the movement helps with the algae, it also keeps your tank active and interesting. Lots of other algae eaters (like nerite snails) don’t move much they are more like stationary.

These fish are great for novices, they make it much easier to keep the tank clean and their behavior is unlikely to be a problem.

That being said, Like any other fish, Siamese algae eaters produce waste. Overstocking might make your tank messier, not cleaner.

Typical Behavior

Most of their time is spent in the lower tank levels. They swim around here until they find a spot covered with algae, and they’ll probably sit here until it’s gone. 

If you keep a few together they will form groups, and you will find them feeding in the same area together. 

They are rarely aggressive but they are quite energetic and swim fast. This means they are not supposed to attack other fish, but may disturb and unsettle any calmer species. 

If they are aggressive then watch them closely for a few days, if the problem persists they might need to be separated.


Here is a look of Siamese algae eater

siamese algae eater
Image by Levi76 from commons wikimedia

Usually with respect to the appearance of True Siamese algae eater has a long , narrow body, which can reach up to 6 inches. Usually they ‘re a pale grey or gold with a black stripe spanning from the head to the tail. 

You may find that the stripe begins to fade; this may be during a mating display, times of stress, or a way of camouflage (which is less common in the aquarium) itself. 

There are no differences between males and females until about 3-4 years old and the only thing that gives away their sex is size at this point. In mass, females are about 30 per cent larger than males.

Siamese Algae Eater vs Flying Fox

Since they look so similar, the Siamese flying fox (Epalzeorhynchos kalopterus) often gets mistaken for the algae eater. They have both a bold, black stripe running down their bodies. 

The easiest way to find out which species you are looking at is to check the corner of your mouth for flaps.

They have flying foxes but algae eaters are not. But this is almost impossible to check when the fish are alive and swimming around, so by looking at the color, you can make an educated guess. 

Here is an article on Oscar fish

Habitat and Tank Conditions for Siamese Algae Eater

On the flying fox, the black stripe tends to be smoother and it ends where the tail fin starts. The eater’s algae is less uniform and extends to the end of the tail fin.

In the wild, Siamese algae eaters are found in Southeast Asia’s densely planted rivers and streams. These are the same habitat preferences of Asian Carp which is closely related. 

These tropical waters are slightly acidic and have no tendency to have a rapid current. Under the surface you’ll find lots of sheltering plants, rocks, and logs. 

The time of an algae eater is split between hiding in those shelters and looking for food surfaces. This is mostly algae but also other things that sink to the river’s bottom. 

They are not the best explorers, they tend to stay around shelters that they are familiar with and rarely venture up to the water’s surface.

You might want to check out this article Iridescent shark

Siamese algae eater Aquarium care

They are active and fast swimmers who, if kept in a group, go to school together, but some individuals may display aggression against their own kind or related fish.

The red algae-eater can generally be kept in most community tanks and is reportedly much less aggressive than similar fish like the Chinese algae-eater or the red tailed black shark.

It prefers a 24–26 ° C (75–79 ° F) water temperature range, a 6.5–8.0 pH range, and a 5–20 dH water durability.

Because the red algae-eater is effective in controlling tank algae, many aquarists like placing them in heavily planted tanks with high lighting to prevent algae growth.

The red algae-eater is valued for its ability to eat red algae as opposed to other aquarium algae eat fish. Nevertheless, the fish is an opportunistic feeder and will eat pellets and most other foods, a trend that strengthens with age.

The tank lid should be properly closed so there is no large hole for the fish to jump out of the tank. 

They love driftwood / rocks and some plants that can support their weight to rest on because they can’t stay in mid water. 

Siamese algae eaters often go to school together, but they are happy to live solo as well. When two are held together, as they mature, they will often establish their own territory.

They can be a long-lived fish, with lifespan reports up to 10 years.

Siamese algae eater tank condition

A sandy substratum makes it safer for them to swim around without scratching their bodies or damaging their sensitive barbels, as they spend most of their time near the bottom of the tank. 

Add plants to make them feel at home. They act as shelter while maintaining cleaner, oxygenated water. 

There is a chance that some of the plants will start nibbling your fish if they can not find any other food.

The best way of protecting your plants is to keep them well fed. One strategy is to use species that are fast growing, like hornwort, that can recover quickly if any parts are eaten. 

All fish like to have somewhere that they can hide from their tank mates, especially the bottom-dwelling fish.

Create caves around the tank to provide them with an escape. They are not territorial, so there should be no quarrels about who goes where. 

Most fish can jump, but some may do better. Siamese algae eaters are active and fast making jumping from the water easier for them.

Keeping a lid on the tank ensures you don’t make a fatal escape attempt to come home. To keep the water within a 75-79°F range you will need a heater. Durability of water should be 5-20 dH. 

Ideally the pH would be between 6.5 and 7.0, but if necessary they can tolerate a slightly larger span (about 6.0-8.0).

They have no special requirements for water flow, which might be surprising since they are naturally living in rivers. These would be slow moving and the current at the bed of the river where they live would be even weaker.

Siamese algae eater tank mates

Siamese algae eaters are peaceful creatures which means a long list of potential tank mates is available. This makes them good candidates for an aquarium within the community. 

As these fish spend their time at the bottom of the tank, you also need to think about what else is going to be living there. Lots of low-inhabitants can be territorial, or just bully those who get in their way.

Red tail sharks are a good example of this; when they mature they harass others to protect their territory. This is not a battle which would win your peaceful algae eaters. 

There are plenty to choose from peaceful bottom-dwellers. Corydoras are among the most popular; they contain many different species in this genus.

Fish that live in other areas of the tank will have no disputes over territory so there’s an even wider selection. Do not add any notoriously aggressive fish, because they may attack or eat your eaters of algae. 

This usually means avoiding cichlids, many of which should be kept in a tank of only one species anyway. However, there are some quiet exceptions, like angelfish ones. 

Tetras, danios, and guppies work well because they’re not aggressive, and small. You can also use bigger fish such as gouramis and barbs, as their size does not come with aggression added. 

It’s good to remember that your mates in the tank need not be fish. You can add other animals, most of which tend to eat algae too.

Shrimp (amano, cherry, and ghost) and snails (such as nerite snails) are the most common. 

Mixing with your fish in shrimps and snails offers some different behaviors, adding extra interest to your tank. They still contribute to the tank ‘s biological charge so don’t overfill your aquarium.

Keeping Siamese Algae Eaters Together

More than one Siamese algae can be kept eater in the tank. In schools of at least 4-6, they show off their best behaviors. 

However, this does not mean you need to keep them in a school, they do well if they are kept individually or in pairs too.

Siamese algae feeding

The bulk of your diet is in your name. They ‘d be eating algae, plant matter and vegetation in the wild but they’re not just herbivores. They are scavengers so they’re going to eat anything they find, including dead fish and insects. 

In the aquarium, it’s easy to provide them with, they ‘re not fussy and they’re going to eat most of the things that you add to the tank.

This includes food from store flakes and pellets, algae wafers, and live foods. The brine shrimp and blood worms are good examples of live foods, frozen varieties will work well too. 

Sinking foods such as pellets are good for bottom-dwelling fish, because they are more likely to fall higher up in the tank past fish.

Overfeeding can be an issue because before feeding time, they already have some algae and plants in the tank.

Sometimes if you keep adding too much, Siamese algae eaters will stop eating algae in favor of the other foods that you give them. 

They can eat a lot, if you allow them, they would eat all day. Limit feeding to a quantity that they can easily complete in a few minutes each day.

Siamese algae eater care guide

There are no specific diseases to which this species is prone, but that does not mean that at some point they will not get sick. 

Most illnesses give signs, some are more evident than others. The common Ichthyophthirius multifiliis parasite (generally known as “I”) causes small white dots around the body , for example. 

Lots of diseases have treatments and medicines that you can buy that work well with quarantine tanks, but there are ways to help prevent diseases from getting into your siamese algae eater.

High quality food is less likely to cause problems with the organs. Cheaper food can cause constipation that often leads to additional effects. 

Dirty water is like humans breathing polluted air, so changes to water should be made every two weeks to reduce pollutant buildup. 

Pay attention to what you are adding to your tank. Decorations can carry toxins, and diseases may result from water from other aquariums.

Siamese algae eater Breeding

It’s unlikely you’ll be able to breed these fish yourself, even though they match lots of other fish in the same way. They ‘re only known to raise hormones in farms. 

It is hard enough to just sex them and needs a keen eye. Once fully matured, females are about 30 per cent larger. 

It is likely that spawning could be triggered by changes in water conditions ( temperature, pH, etc.), but little is currently known about how to breed them in home aquariums.

Siamese algae eater size

The size of siamese algae eater algae is it can reach up to 6 inches. 

Siamese Algae eater Price

The price of siamese algae eater is around at around $3-$5 a fish. Due to its popularity most pet stores sell them, so they are easy to find. They are also quite cheap.

Concluding Thoughts

Are Siamese Algae Eaters Your Aquarium Suitable? 

You shouldn’t have a problem with keeping Siamese algae eaters happy and healthy, whether you’re new to fish keeping or have been doing it for years. 

They are peaceful and hardy so they are less likely to fall victim to mistakes made by the beginners. If your tank contains plants, quiet fish and sufficient free space, they will thrive. 

Your aquarium will seem cleaner and more active in return.

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