Siamese Algae Eater care guide

Siamese Algae Eater (lat. Crossocheilus oblongus) is a fish of the Cyprinidae family. It is often called SAE, fish which is an abbreviation from its full name. It is used in aquarium husbandry as a natural way of fighting unwanted algae. It is considered the most efficient of all known algae eaters. The fish is peaceful, not very large, and it is a true tank cleaner. It eats algae in a tank, and this task is quite challenging since not every fish can do it.

Habitat in the wild

Earlier it was considered to belong to the Epalzeorhynchus genus according to scientific classification. Now, it belongs to the Crossocheilus genus, but the fish itself is important, not its name.

Thailand and the Malayan peninsula are Siamese Algae Eater habitats. This fish is the only known fish genus that can eat coarse algae, and it will be a good helper for you to deal with black beard algae (BBA) in a tank.

Crossocheilus oblongus lives in fast streams and rivers with a rocky bottom that consists of fieldstones, gravel, and sand with many snags or tree roots. Low water level and transparency create favorable conditions for blusterous algae growth, and the fish feeds on them.

Scientific NameCrossocheilus oblongus
Common NamesSiamese algae eater; sae fish
Range and habitatMalayan peninsula
Size16 cm (6.3 in)
Lifespan10 years
Ease of keepingEasy
Minimum tank size200 liters (44 gallons)
Temperature24–26 °C (75–79 °F)
Water hardness5-20 dGH


In the wild, siamese algae eater may grow up to 16 centimeters (6.3 in) large, while it is usually smaller in a tank – up to 12 cm (5 inches).

It has an elongated silvery-colored body with a dark stripe. The fins are almost transparent without any visible color or tint. The black stripe starts from the nose tip and goes till the tail fin end. When the SAE fish is stressed, the stripe becomes light-gray.

The tripe is not perfectly straight, and it has visible notches. Above the black stripe, if looking at some specific angle, you may see one brighter colored stripe. There is a pair of barbs on the fish underlip. Its jaws allow SAE fish to scrape algae fouling from plants, decorations, and tank equipment.

True Siamese algae eater vs. siamese flying fox fish

Except for Siamese algae eater, you may also encounter another fish – Flying Fox (Epalzeorhynchos kalopterus) on sale. The thing is that these two fishes are very much alike, and quite often, one is taken for another.

And now you are going to ask: so what’s the big difference? The difference is that flying fox deals with tank algae not as good as SAE fish, and what is more important, unlike SAE fish, this fish demonstrates aggressiveness towards its tank mates. Therefore, it is less welcome in community tanks.

Once you know what you should pay attention to, you’ll easily tell between these two fishes.

The main feature of the fish is a black stripe along its body. True Siamese algae eater has denticular shaped black stripe that starts from the fish mouth and ends on the edge of its tail fin. As for the flying fox, its black stripe ends on its body where the tail fin starts (the fin is transparent). All upper side of the fish body has a brown tint, and each scale has dark edges, which makes its body pattern look reticulate.

Siamese algae eater has a pair of thin forward barbels, but they may rest on the fish cheeks when it swims or relaxes. Adult flying fox species have red coloring around their mouth.

A true SAE fish has three support points when it lies on a tank bottom – these are its tail and abdominal fins at that the fish doesn’t touch the substrate with its pectoral fins.

Siamese algae eater vs. algae

Quite often, algae turn into a real problem in a tank. Many approaches are used to fight them, one of which is biological – using fishes eating the unwanted vegetation. SAE fish is very efficient in cleaning the tank from inferior plants.

This is the only fish kind kept in tanks capable of stopping algae attack at the very beginning. Its mouth is made to capture young algae. Those that are at later stages of development don’t interest the fish.

The same is true about green fouling on tank walls. SAE fish can’t deal with it, but many catfishes such as bristlenose pleco or sailfin pleco can.

To maintain a small tank in ideal condition, two SAE fish are enough. At that, young species deal quite well with algae while adults prefer more nutritious food, and they are less efficient against algae.

Difficulties in keeping

The fish is a peaceful, active, and not demanding one. Besides, it is one of the few who can fight algae in a tank. The main siamese algae eater peculiarity is that it can eat black beard algae, unlike other fishes, which don’t even come close to this kind of algae.

However, to make siamese algae eater eat BBA, the fish should be half-starved, which means you should overfeed it. Juveniles eat black beard algae more eagerly, while adult species prefer live or artificial food.

Keeping in a tank


Siamese algae eater lifespan is about 10 years, which is quite long for a tank fish. It is active and spry, but it likes to have some rest from time to time. It tends to choose several tank plants with wide leaves to rest on them. The juveniles may use narrow leaves of tank plants for the same purpose. If there are no proper plants in the tank, they rest on the tank bottom.

Tank size

Siamese algae eater is rather not picky. Due to its relatively large size, a couple of adult SAE species requires a tank not less than 200 liters capacity. They are extremely lively and juice up the tank scenery.

SAE fish likes free-floating in the wild and behaves timidly and fearfully if kept separately from other fishes or small groups. The fish feels more comfortable in a group of 5-6 or more species (depending on the tank volume). In this case, you’ll be rewarded with a more natural appearance and behavior of the fish, plus the chance to observe how fish interact in a group.

Water parameters

Siamese algae eater can live at a wide range of water parameters, but it prefers neutral or a bit acidic water. Recommend water temperature is between 24–26 °C (75–79 °F), acidity – pH 6.5-8.0, and a water hardness of 5–20 dH. The fish prefers well-circulating water reach with oxygen.

Weekly water renews (up to 30% of the tank volume) are a must. Don’t forget that tap water is often a source of such toxic components for the fish as chlorine and high-density metals. Thus during every water renewal, use water conditioned that in a moment makes the water suitable for its dwellers. It removes toxic substances and enriches water with vitamins.

Tank setup: decorations and plants

It is desirable to have not a high but a long thickly-planted tank with noticeable water flow. Since SAE fish typical biotope is a well-lighted fast-flowing stream or river, the tank water should be crystal clear and rich in oxygen. This means that if there are some areas with backwater and poor oxygen content in the tank SAE fish won’t feel comfortable there.

They are active; however, their air bladder’s construction doesn’t let them stay in the water all the time. Siamese algae eater can be often seen lying on the substrate or large leaves of tank plants. Thus, it is recommended to organize the tank, so it has bunches of live plants and enough space to swim.

The fish can easily jump out from the tank, so it is required to cover it with a glass-cover slip or put some fluctuant on the water surface.

You can use small-sized gravels as a tank bottom substrate, and put some snags or stones into the tank is also a good idea. Lighting doesn’t play an important role. Both bright and scattered light is good for the fish. For this reason, when selecting lamps for the tank, you should keep in mind the tank plants requirements.


Since the wild siamese algae eater inhabits ponds with circulating water, they prefer clean water rich in oxygen. To swim around the tank, SAE fish needs water flow since it reminds the fish of its natural habitat. If there is no flow in the tank, you can create it using a powerful canister filter. Don’t forget about daily water renews (about 30% of the tank capacity).


In the wild, SAE fish mainly feeds on plant food. In a tank, it scrapes algae from tank plants, decorations, and equipment. At that, small and large tank pants don’t get damaged at all.

When in a tank, the siamese algae eater eats all types of live, frozen, and dry specialized food. SAE fish should have a diversified diet with a large amount of plant food in it. If the plant component content in the fish diet is not enough, it may start eating tank plants, especially moss types. Juveniles eat algae more eagerly, while adult species prefer protein food most.

For proper growth and development, SAE fish must additionally get well-balanced food with necessary nutrients and vitamins and contain plant components. Also, you should keep in mind that they are bottom feeders, so the food should quickly get to the tank bottom.

Tank mates

SAE fish is a good-tempered fish, and it can be a decent tank mate for most unaggressive fishes, though it’s better not to keep it with long-finned ones since siamese algae eater may nip their fins.

As for unwelcome siamese algae eater tank mates, this is a rainbow shark. The thing is that both species are related and territory-dependent ones. They inevitably will have fights, and it’ll end up with the death of one of them. Males show territory dependence towards each other. Therefore it’s better not to keep a lot of males in a small tank.

Since the fish is very active, it’ll be a troublesome tank mate for cichlids that guard their territory during the spawning period, and SAE fish will disturb them all the time by swimming around.

In the wild, siamese algae eaters practice free floating, and they may be quite timid and hesitant when kept separately or in a small group. The optimal group size is 5-6 species or more (depending on the tank capacity). You’ll be rewarded by seeing more natural fish appearances plus interesting behavior and interaction between them.

Gender differences: male vs female

Siamese algae eater has rather poorly pronounced gender dimorphism, though adult fish females are fatter than males and look more rounded if you take overlook. Yet, for now, there are no other distinctive features you may use to tell between the fish male and female.


There is no reliable information about siamese algae eater breeding successfully in a home aquarium (without hormonal agents’ support). The species you see on sale are either bred in fish farms or were caught in the wild.