Siamese Algae Eater (Crossocheilus siamensis)

Siamese Algae Eater (lat. Crossocheilus siamensis) is a peaceful, not very large fish and it is a real tank cleaner. The fish is often called SAE, which is an abbreviation from its full name. The fish eats algae in a tank and this task is quite challenging, since not every fish can do it.

Except siamese algae eater you may also encounter another fish – flying fox (Epalzeorhynchus 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 and what is more important, unlike SAE this fish demonstrates aggressiveness towards its tankmates. 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 SAE fish has denticular shaped black stripe that starts from the fish mouth and ends on the edge of its tail fin. As for flying fox, its black stripe ends on its body where the tail fin starts (the fin is transparent).

All upper side of the body has 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 cheeks when it swims or relaxes. Adult Flying Fox species have red coloring around their mouth.

A true SAE 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.

Habitat in the wild

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

Thailand and Malayan peninsula are SАЕ 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.

Siamese algae eater lives in fast streams and rivers with rocky bottom, that consists of field stones, gravel and sand with large number of snags or tree roots.

Low water level and its transparency create favorable conditions for blusterous algae growth and the fish feeds on them.

Difficulties in keeping

The fish is peaceful, active and not demanding one. Besides, it is one among the few fishes, who can fight algae in a tank.

The main 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 SAE 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 food.

Keeping in a tank

Scientific NameCrossocheilus siamensis
Common NameSiamese algae eater, SAE
Tank size30 gallons and more
DietOmnivorous bottom feeder
Temperature24–26 °C (75–79 °F)
Sizeup to 6 in (15 cm)

Is a very strong and enduring fish, that can adapt to a wide range of tank conditions. Just like all other tank fishes it feels comfortable in a thickly planted tank that has open spaces to swim.

The fish grows up to 6 inches long (15 cm), at that its lifespan is about 10 years.

To swim around tank SAE needs water flow, since it reminds the fish its natural habitat. If there is no flow in the tank, you can create it by means of powerful canister filter.

This fish 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, the fish rest on the tank bottom.

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.

Epalzeorhynchus siamensis likes free floating in the wild and behaves timidly and fearfully if kept separately from other fishes or in 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 more natural appearance and behavior of the fish plus the chance to observe how fish interact in a group.

True SAE have peaceful temper and get along well with most of other peaceful fishes. Sometimes they may nip fins of long-finned fishes, but this is very seldom the case.

Compatibility and tank mates

SAE is a good-tempered fish and it can be a decent tankmate for most of 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 SAE tankmates, 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 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 spawning period and SAE will disturb them all the time by swimming around.


In the wild 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 fish eats all type of live, frozen and dry specialized food. SAE should have a diversified diet with large amount of plant food in it.

If the plant component in the diet is not sufficient, fish may start eating tank plants, especially some types of moss. Juveniles eat algae more eagerly, while adult species prefer protein food most.


Siamese algae eater have rather poorly pronounced sexual dimorphism, though adult 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 male and female.


There is no reliable information about breeding successfully in a home aquarium (without hormonal agents support).

The species you see on sale are either bred in farms or were caught in the wild.