Siamese Algae Eater: The Ultimate Care Guide

The Siamese Algae Eater (Crossocheilus oblongus) is a popular fish to keep in the home aquarium. Not only are these peaceful fish beautiful, but they are also very good at keeping your tank clean of algae! In addition to their practical benefits, they can be quite entertaining to watch. 

Siamese Algae Eaters tend to live in small groups and will often swim together around plants and decorations near the bottom of the tank. When startled by movement outside the aquarium, they may school together as if trying to hide or find safety in numbers. They are very active and enjoyable species, which adds an interesting dynamic element while you observe them throughout their day-to-day activities!

Unfortunately, these fish are often confused with Chinese Algae Eater (Gyrinocheilus aymonieri). Both of these fish have a similar body shape but the patterns on the Siamese Algae Eater are sharp which makes them more beautiful.

In this guide, you will be provided with the right information about Siamese Algae Eaters and the right way to care for these species. 

Species Profile & Overview

The Siamese Algae Eater (Crossocheilus oblongus) is a freshwater fish native to Southeast Asia. More specifically, they are native to the Malay Peninsula, Mekong, and Chao Phraya rivers.

In the wild, they prefer rivers that have slow to moderately slow and lots of greenery. This has caused them to develop a craving for algae and other plant matter in their diet. These fish are also known for eating black beard algae that not many fish can eat.

They are very peaceful species and will not harm other fish in the tank. But they are always on the move, whether it’s to find food or chase after the other inhabitants of the tank.

Because of their ability to eat large amounts of algae without harming live plants, these fish have gained popularity among aquatic enthusiasts. That’s why they’re the best option for people who constantly battle algae growth in their aquariums. Especially with black beard algae!

In addition, when compared to many other tropical fish species, these fish are surprisingly hardy and low-maintenance. Which is why they are so common species to own among first-time fish keepers. 


Siamese algae eater
Siamese algae eater

The Siamese Algae Eater is one of the most beautiful species of algae-eating fish coming from Southeast Asia. Their cylinder body is almost similar to other species of algae-eating fish living in that area but the sharp black line on the sides of their body sets them apart. 

Their body is slim cylindrical shapes, with large eyes and fins that are in scale with their length. Its yellowish skin is painted with a sharp black stripe that makes the fish stand out. The fins are mostly transparent and have no colors but, in some cases, the fins will have an orangish tint.

Other than the beautiful black line they have, the most distinctive aspect of their appearance is unquestionably their mouth. The Siamese algae eater, like its South American pleco relatives, has a downturned mouth that it uses to cling to surfaces. 

Siamese Algae Eaters, in general, are beautiful additions to any aquarium, especially one with an algae problem. They will not expand excessively in size, so they are ideal for tanks with limited space. 

Adult Size

Siamese Algae Eater typically grows to be around 6 inches in length. If you’re planning on keeping this fish, you’ll need a tank that can hold a sufficient amount of water.

The growth rate of the Siamese Algae Eater varies depending on diet, water quality, and other environmental factors. In general, they can reach their full size within 1 – 2 years if cared for properly. 

It’s important to provide them with plenty of vegetation such as algae wafers or blanched vegetables which are essential for their health and growth rate.


The Siamese Algae Eater typically has a lifespan of 5 to 10 years when kept in optimal conditions. Factors such as water quality, tank size, diet, and handling can all influence the longevity of this species. 

Poor water quality will reduce its life expectancy while good-quality water with regular maintenance can help it live longer. Additionally, the tank size should be large enough for these active swimmers to move around freely.

Overcrowding or inadequate space can lead to stress and health problems which eventually shorten their lifespan. A balanced diet consisting of both plant matter and animal protein is essential for its growth and survival. 

Lastly, proper handling techniques must be followed when netting or transferring them from one aquarium system to another in order to prevent injury or shock which could potentially cause premature death.

Behavior & Temperament

Siamese Algae Eaters are very active and energetic fish that love to swim around the tank. They will usually spend most of their time grazing on algae, but they can also show aggression toward other fish in the tank. 

Therefore it’s important to consider a proper tank setup for them to remain calm at all times. In order to create a suitable environment for Siamese algae eaters, we highly recommend the “Care” section of this guide. 

Siamese algae eaters are active and undeniably social creatures. Typically spend their time on tank bottoms and on other objects. They will also non-stop swim around looking for food. This makes them very fun fish to own.

While these fish are not typically aggressive, you should be aware that their constant movement can be stressful for their tank mates. This can be solved by providing enough places for the fish to hide. 

Siamese algae eaters are technically schooling species and they prefer to live in a group. But keeping multiple Siamese together in a small place like an aquarium can be a challenge. These fish can show territorial behaviors when multiple males are present in the tank. So to keep a group of them you will need a large aquarium that can house a number of these fish. 

Siamese Algae Eater Care

There isn’t much maintenance involved with keeping a Siamese Algae Eater as a pet. And hence, they are a fantastic addition to any home aquarium, as they aid in maintaining a healthy environment by eating algae. 

Also, they are extremely resilient and adaptable, able to thrive in a wide variety of water environments. Still, it’s crucial to furnish the area with numerous concealing elements and ornaments. which will be covered in greater depth soon in this guide.

Tank Size

The minimum tank size for a Siamese Algae Eater fish is 30 gallons. It’s best to keep only one of these fish in a 30 gallon aquarium. These fish grow slightly fast and more than one of them can’t live in a small tank like that. 

As we mentioned earlier, these fish prefer to swim in a school, so if you have a larger tank we definitely recommend getting a few of them. The number of fish you want to keep depends on the size of your tank but generally add one extra Siamese every 20 – 30 gallons your tank can hold. 

This is because these fish are quite active and bottom dwellers so they need plenty of bottom space. A large aquarium allows them to live peacefully without having to fight for their space. 

What To Put In A Siamese Algae Eater Tank

When aquascaping for Siamese Algae Eater, it’s important to make an effort to recreate conditions as close as possible to those in their native habitat. This involves making use of natural features like rocks, driftwood, and plants to construct a concealing cover. 

There should be plenty of open swimming space in the aquarium as well as open bottom space so the fish can stay active and healthy. Plants and other natural decor are ideal for an aquascape housing Siamese Algae Eater.

Plants are important for providing oxygenation, shade, and food for the fish, as well as adding visual interest to the tank. Adding some bright-colored gravel or sand will help complete the look of your aquascape while also making it easier to clean up any messes made by these active little creatures!

Try to keep everything natural as these decorations can help to create a more realistic and natural-looking aquarium. Natural decorations can also have beneficial effects on water quality.

Some live plants that are compatible with Siamese Algae Eater fish include Buce Plants, Anubias, Java Fern, and Vallisneria. To keep these plants thriving in the tank, you should make sure to provide them with adequate lighting and fertilize them regularly. 

Even though these fish are great algae eaters, you will still need to put in some work if algae are the only reason you want to have these fish. To stop algae growth, it’s best to remove any dead leaves or stems as necessary and let these fish eat the rest. While these fish do consume algae, they can not eradicate algae all by themselves. 

Siamese algae eater
Siamese algae eater

Light Requirements

Siamese Algae Eater is a freshwater fish species native to Southeast Asia which means similar lighting is necessary. To make these fish look their best, they need the light that provides a natural day/night cycle of 10-12 hours of light per day.

This will mimic the natural environment in which this species evolved and help them show off their beautiful colors and patterns. 

High-quality lighting also helps plants grow by providing the necessary wavelengths for photosynthesis, increasing the growth rate, color intensity, and overall health of aquatic plants in an aquarium setting.

When buying a light, consider the intensity of the light as well as its spectrum. LEDs are great because they produce less heat than regular bulbs. But you should still make sure that whatever type of light you choose has a good intensity that helps your aquatic plants to grow. 

Water Conditions & Parameters

Siamese algae eaters are resilient species that are quite versatile. They can survive in a variety of water conditions, but it is crucial to match the water conditions in the tank as closely as possible to those in their native environment. 

This will give them the best opportunity to thrive in your aquarium setting. This will reduce their exposure to any health risks associated with being in an improper setting and will reduce stress. 

Additionally, for maximum health, they require lots of oxygen in the water, so make sure your aquarium is well-aerated. While it’s crucial to match the aquarium water to the waters in the animals’ habitats, we should emphasize that maintaining a stable tank is much more important. 

Considering these points, here are the ideal range of parameters for Siamese Algae Eater:

  • Temperature: 74 – 80 Degrees Fahrenheit
  • pH: 5.8 – 8.0
  • TDS: 50 – 200 PPM

Weekly water changes are necessary to maintain the tank’s health and the residents’ safety. According to the size and stocking of your tank, you should replace between 10 and 20 percent of the water there each week.

Filtration System

Having a reliable filtration system is essential for the health of your Siamese algae eater. A high-quality filter can assist clean the water of any leftover food, waste, or other organic debris. 

This aids in maintaining nitrate levels low and oxygen levels high, both of which are essential for fish health. Additionally, it reduces the buildup of ammonia, which is something that can be harmful to fish. 

It’s vital to think about the filter’s flow rate, media type, and upkeep needs before making a final decision on an aquarium filter. To adequately filter your tank, the flow rate should match the size of your tank. 

Last but not least, pick a filter that doesn’t need much upkeep so that you don’t have to waste time and money replacing parts or cleaning them frequently. 

Taking all of these factors into account, we advise getting a canister filter for your Siamese algae eaters. These filters can be used with minimal effort and produce excellent results. They do an excellent job of digesting waste products like ammonia and keeping the tank tidy. 

Common Diseases and Prevention

There are a number of diseases that can affect Siamese Algae Eater fish in an aquarium. One of the most common is Ichthyophthirius multifiliis (Ich), a protozoan parasite that can create white spots on the body of the fish. 

Bacterial infections, fungal infections, and parasite infestations are also major causes of illness. Stress from overcrowding the tank or subpar water quality are two possible causes of these illnesses. 

When left untreated, these conditions can lead to a lack of appetite, drowsiness, difficulty breathing, skin sores, discoloration, fin rot, and even death from secondary bacterial infection. 

A major cause of fish illness is bad water quality. Internal and external disorders can be brought on by high concentrations of ammonia and other contaminants. Keep the aquarium water clean and healthy to stop the spread of disease. 

You can stop the disease from expanding in your tank by quarantining any new fish beforehand and keeping the tank clean at all times. Diseases can be introduced to your tank by new fish but poor water can trigger an outbreak.

Diet and Feeding Requirements

The Siamese Algae Eaters are omnivore species. The majority of their diets consist of algae and other plant matter but they will also crave protein-rich foods as they become older. 

Algae, tiny crustaceans, and insect larvae make up the bulk of their diet when foraging in the wild. They either graze on plants and other surfaces for algae or scavenge through the substrate of the aquatic body in which they reside to get food. 

In captivity, they require a diversified diet including high-quality flake food, alga wafer, freeze-dried bloodworms, and live or frozen brine shrimp. Overfeeding can cause them to stop consuming algae, so try feeding them once daily.  

Breeding Siamese Algae Eater

Breeding Siamese Algae Eaters is possible but it’s a difficult task that should only be attempted by experienced fish breeders. These creatures can get quite large and must be kept in groups for successful breeding, making it a complicated process.

In captivity, recreating the water conditions and simulations necessary to trigger breeding behaviors in certain species can be difficult. Mimicking the natural events that take place in their wild habitats is not a simple task that inexperienced breeders can create!

At the same time, these fish are sold at a very affordable price in pet stores which makes breeding them unprofitable. This low price point has discouraged many breeders from attempting to breed these fish, resulting in limited information available about the specifics of breeding these fish in captivity.

Tank Mates

Siamese algae eaters are peaceful, community-friendly fish that prefer to hang out at the bottom of the tank. However, the vast majority of bottom-dwellers are a bit territorial in nature and need the bottom of the tank to be free. 

Other than that, these fish are not picky about the water column fish you want to add. A wide variety of freshwater creatures enjoy their company because of their calm demeanor.

Considering these, here are our top picks of tank mates for Siamese Algae Eater:

Siamese algae eater
Siamese algae eater


The Siamese algae-eater is a popular freshwater fish for its unique coloration and hardiness. It is also an excellent choice for helping to control the growth of algae in aquariums, as it actively grazes on most kinds of soft algae. In addition, this fish can live peacefully with other species, provided they are not overly aggressive or territorial. As such, the Siamese algae-eater makes an ideal option for any aquarist looking to add some life and beauty to their tank while keeping its environment clean and healthy.

References & Useful Links:

  1. Crossocheilus
  3. Aquarium info