Siamese Algae Eater (SAE) Care Guide


The Siamese algae eater (Crossocheilus siamensis), is one of the most popular “algae eater” fish in the tropical fish hobby. They’re famous for their ability to eat “Black Brush Algae” or BBA. This stiff, red algae can overtake planted aquariums and is resistant to normal algae control measures.

Siamese algae eaters (SAEs) are easily confused with the Chinese algae eater Gyrinocheilus aymonieri and the Red algae-eater Crossocheilus langei. Crossocheilus comes from the Greek Krossós (tassel) and cheílos (lip).

Siamese Algae Eater (SAE)

On average, Siamese algae eaters grow to 2.7 to 3 -inches (70-75 mm) at maturity. SAEs have a black band running along the body. The band starts at the snout and continues through the clear section of the tail. The fins of Siamese algae eaters are clear. It is difficult to find true Siamese algae eaters in fish shops.

Siamese Algae Eater

Natural Habitat

Siamese algae eaters are native to Asia and are commonly found in Chao Phraya and Mekong basins, Thailand and Cambodia. The fish will also swim into flooded fields during the rainy seasons. Some of these natural waters have a very low pH (5.0) and almost no water hardness.

The fish inhabit fast-moving streams. These habitats have a substrate of sand, pebbles and boulders. Tree roots are also common structures. Crossocheilus graze on “aufwuchs.” This word is a biological term for a mat of living green algae, diatoms and microorganisms that live on submerged surfaces like stones and logs.

SAEs position themselves in areas of high flow, attaching to smooth surfaces with their sucker-like mouth. Siamese algae eaters and other tropical fish are used in Prahok, a salty fermented fish paste used in Cambodian cuisine.

Siamese Algae Eater plants

Aquarium Requirements

Siamese algae eaters can be housed in a typical community tank, but they really like a biotope aquarium that resembles a tropical stream. The ideal aquarium would be twenty-gallons or larger.

The substrate would be a combination of gravel with pebbles and a larger “boulder” along with driftwood. This creates a network of roots and branches arranged to form cover and shaded spots for the fish to explore.

Live plants look great and provide the ideal feeding stations for SAEs. The surface of aquarium plants is coated with bacteria, zooplankton, worms and other organisms that serve as food for the fish. Even though it looks like they’re grazing on algae, the fish are getting a bellyful of live plant and animal matter. Bolbitis and Anubias can be attached to driftwood with cotton string.

The fish love stronger water currents so these plants thrive in a fast-current environment. Many other tropical fish come from a similar environment and will thrive in an aquarium like this. It a fast-moving stream is not your type of aquascape, have no worries! SAEs will be happy in a calmer planted tank with large-leafed plants like Amazon swords. The fish will even graze on plastic plants!

Water Conditions

Experienced aquarists recommend keeping the aquarium water very clean when keeping Siamese algae eaters. Many novice fish keepers thing “algae eaters” are garbage consumers that live in the worst conditions. This is a false notion. SAEs come from pristine streams with very little suspended solids and organic pollination. They thrive when the water is clear, and the aquarium is free of sludge build-up.

Siamese algae eaters don’t require special water chemistry requirements. The fish can be kept in a wide pH range, ideally around 6.5 to 7.5. Water hardness and alkalinity (carbonate hardness) are not critical. A range of 5 to 10 degrees is ideal, especially if you’re keeping a planted biotope aquarium. Many compatible tropical fish come from soft, acidic waters.

Many advanced aquarists use reverse osmosis water to recreate these conditions. Be aware that with low in carbonates (1-2 degrees), the pH can drop over time. Acids from natural biological processes will neutralize alkalinity and lower pH. Maintain at least 3 degrees of KH to prevent the pH from dropping below pH 6.5.

Siamese algae eaters cannot tolerate ammonia or nitrite. These substances must be kept at zero at all times. Chronic exposure to even low levels weaken the fish’s immune system, leading to bacterial and parasitic disease problems. Partial water changes, made every three to four weeks, will replenish alkalinity, stabilize the pH and dilute nitrate and dissolved organics.

Siamese Algae Eater and Water Chemistry Parameters

pH:6.0 – 8.0
General or Total hardness:5 – 20 degrees
Alkalinity or carbonate hardness:5 – 20 degrees
Water temperature:77 – 82°F (25 – 28°C)
Ammonia & Nitrite:0.0

Siamese Algae Eater and Water Temperature

Like all tropical fish, Siamese algae eater require a stable water temperature when kept in an aquarium. Minor fluctuations are normal and even happen in the fish’s natural environment. But dramatic chills must be avoided. Chilled fish are especially susceptible to external parasites like ich. An aquarium heater prevents temperature drops that stress fish.

Tap Water Safety

Chlorinated tap water is toxic to aquarium fish. Chlorine disinfectants are oxidizing chemicals deigned to destroy microbes in the water. Even trace amount of chlorine will react with delicate gill tissue, harming the fish. Use a water conditioner to neutralize chlorine and chloramine.

Copper pipes inside the home often releases copper into the water. While trace amounts are necessary in the fish’s diet, too much can poison the fish. Most water conditioners will detoxify a small amount of copper, but some water sources have high levels. Before using the tap water, flush the faucet for a minute or two. This drains the pipes of water and reduces the level of copper coming out of the faucet.

Water Filtration

Crossocheilus siamensis are native to clean, well-oxygenated streams. The fish do not tolerate dirty aquariums with a lot of sludge build-up. Poorly-filtered aquarium water is usually discolored due an accumulation of dissolved organics.

If you want to your SAEs to remain healthy and active, the water must be very clear and clean. Use activated carbon or a carbon-resin blend to remove dissolved organics. Foam or fiber cartridges or sponges will capture floating debris.

For smaller aquariums up to 30 gallons, a HOB filter will be sufficient if the filter cartridges are changed monthly. Make sure the HOB filter is slightly over-sized for the aquarium. This will give you plenty of water circulation in the tank. High-quality HOB filters have a flow control vale. This comes in handy of you want to reduce the flow rate during feeding and tank cleaning.

Larger aquariums benefit from a canister filter. Canister filters are larger and hold more filter media than HOB filters. Canister filters have powerful water pumps and create a stream-like current in the aquarium. Some canister filters have adjustable nozzles so you can create a river-like water flow pattern in the aquarium.

Siamese Algae Eater lighting

Siamese Algae Eater Aquarium Lighting

If you’re already growing live aquatic plants, your lighting is perfect for keeping Siamese algae eaters. The fish like to eat live algae, so having enough light to stimulate a little algae growth is beneficial.

A community aquarium with plastic plants and dim lighting may not provide enough light to support green algae growth. This won’t harm the SAEs if you feed them with an algae-based food. If you keep a dimly-lit aquarium, you can keep SAWs. But without natural algae, the fish will get hungry. Siamese algae eaters will thrive. Just make sure you feed them with an algae-based food.

Aquascaping for Siamese Algae Eaters

Siamese algae eater is very active fish. Make the aquarium look like a shallow tropical stream with plants, rocks, driftwood and caves. These fish really enjoy an aquarium full of interesting nooks to explore. Smooth stones are a favorite spot to graze on aufwuchs. You’ll often see your fish resting on the pelvic and pectoral fins.

Live plants are best, providing natural water filtration and an ideal feeding spot for the fish. Plastic plants and resin ornaments are OK too. The fish will keep those clean by scraping the surfaces in search for food. These fish have a reputation for jumping. A glass cover is recommended.

Aquascaping Essentials for Tropical Stream Aquarium:

  • Fine gravel in planted aquariums
  • Driftwood for cover and grazing
  • Smooth rocks and pebbles
  • Live plants and mosses
  • Optional glass top
Siamese Algae Eater eating algae

Feeding Requirements of Siamese Algae Eaters

Under ideal aquarium conditions, algae and biofilm will provide enough food for a Siamese algae eater. But if you’re keeping a group of three or more SAEs or your aquarium has very little natural algae growth, you probably want to feed them by hand. They’ll eat flake food if it falls to the bottom of the tank. It is normally not a good idea to allow flake food to settle on the gravel. Wet flakes begin releasing vitamins and minerals into the water, losing their nutritional valve.

Pelletized or tableted algae-based foods are the ideal supplemental food for SAEs. The sinking pellets are best, allowing the fish to graze on the bottom of the tank. The fish’s raspy mouth will scrape off pieces of algae from of the pellet. Pellets will stay intact while submerged than flake food. Pellets retain more of their nutritional ingredients because they’re not wet on the inside. Some pelleted foods can be pushed against the glass after getting a little wet. This suspends the pellet above the gravel so multiple fish can take a bite off the same pellet or tablet. Other fish may want to eat the algae pellets too. It is a good idea to feed surface-feeding tropical fish floating flakes to keep them occupied while the SAEs eat at the bottom of the tank.

Siamese Algae Eater Compatibility

Based on the experience of many aquarists who have experimented with Siamese algae eaters, the following recommendations can be considered reliable:

  • SAEs are gentle and will not bully other fish
  • Chinese algae eaters, often confused with SAEs, will become aggressive and try to attach to other fish in the aquarium
  • Several SAEs will be happy in a 20 to 30-gallon aquarium
  • Pleco-type algae eaters are compatible with SAEs.
  • Avoid large-mouthed fish
  • SAEs won’t try to suck onto the sides of angels and discus.

It’s worth mentioning the Siamese algae eater is considered food by large carnivorous cichlids. Big fish will instinctively try to snap at and gulp down a small fish. If you’ve got big “tank busters” or even small cichlids, it is best to avoid Siamese algae eaters.

The tougher “pleco” type algae eaters are armor-plated and able to survive with most aggressive fish. Note that Plecos have a reputation for damaging broadleaf aquatic plants, like Amazon and Mellon swords. Planted aquarium enthusiasts prefer smaller algae eaters, like SAEs and related species.

Siamese Algae Eaters and Dwarf Shrimps

Dwarf shrimp, like Cherry, Amano and Bamboo shrimps are reported to be compatible with Siamese algae eater. Aquarists have observed SAEs and shrimp for many years and conclude they are good tank mates.

Chinese algae eaters, however, are known to act aggressively toward shrimp. Baby shrimp may be eaten by SAEs if they have the chance. It’s best to remove the fish from the tank if you’ve got breeding shrimp.

SAE with tank mates

Breeding Siamese Algae Eaters

In nature Crossocheilus siamensis are migratory breeders. They remain in freshwater their entire life but move up and down-stream for spawning activity. Aquarists have a difficult time sexing the fish. There have been reports of spawning in aquariums but no fertilization of the eggs by males.

Females carrying eggs will have a rounder belly than the males. But when well-fed, both sexes can look plump. In females have will reabsorb their eggs when not fertilized. Most fish are believed to be wild-caught although rumor says Asian fish farms use hormones to stimulate captive breeding.

Final Thoughts

True Siamese algae eaters are difficult to find in fish shops. If you can purchase them, Siamese algae eaters will keep your plants and ornaments free of unsightly algae and provide entertainment with their interesting, friendly behavior.