The Siamese algae eater ( Crossocheilus oblongus ) is a popular freshwater fish prized for its algae-eating capabilities and peaceful nature. Native to Southeast Asia, this species can be a valuable addition to a community aquarium, helping to keep algae under control. However, proper identification and care are crucial to ensure their well-being and compatibility with other tank inhabitants.
Identification and Similar Species
One of the first challenges in keeping Siamese algae eaters is correctly identifying them. Several species are often mistaken for the Siamese algae eater, leading to confusion and potential problems.
- Siamese Algae Eater (Crossocheilus oblongus): Grows to 6 inches (15 cm) long and has a bold, black line down its side with a tannish-gray back and lighter-colored belly. The black stripe extends all the way from the snout to the tail.
- Chinese Algae Eater (Gyrinocheilus aymonieri): The Chinese Algae Eater can reach 11 inches (28 cm) in length and has a large suckermouth (instead a pointed mouth like the SAE). While they are effective cleaners when young, they become more territorial and aggressive as they mature. For this reason, it's advisable to keep them in a species-only tank in the long term to avoid injury or stress to other tank mates.
- Flying Fox (Epalzeorhynchos kalopterus): The flying fox is much more similar to the SAE in appearance because of its 6-inch (15 cm), shark-like profile. However, it has a thin, shiny gold line that looks like it’s surrounded by two black stripes.
- False Siamese Algae Eater (Garra cambodgiensis): Often called the "false Siamese algae eater" because they really do look quite similar.
It's worth noting that there is also a Crossocheilus species known as C. siamensis, but that one is rarely seen in the aquarium trade. The Siamese algae eaters you can buy are thought to usually be Crossocheilus oblongus, although sometimes a C. langei or C. atrilimes will slip through. Luckily, in terms of care and algae eating capacity, it doesn't really seem to matter which one you get.
Natural Habitat and Behavior
The Siamese algae eater is naturally found in Southeast Asia and can be found in fast-flowing streams and rivers. Being a bottom feeder, it usually stays in the lower water layer. In the wild, they are found in clear streams with lots of algae and biofilm growth on the rocks and driftwood, so provide them with hardscape and other decor to graze and rest on.
The IUCN Red List considers Crossocheilus oblongus to be a species of Least Concern. It does note that habitat loss as a result of logging and palm oil plantations can be a threat.
Read also: The Hoxsey Diet
Technically, the SAE is a shoaling fish that swims together in large groups, but in an aquarium setting, they can be semi-aggressive towards their own kind, especially as they get older and start establishing a pecking order amongst themselves. A single Siamese algae eater can do quite well by itself, but if you plan on buying a group of them, make sure you get at least three or more to spread out the aggression.
Aquarium Setup
Thinking of adding a few Siamese algae eaters to your tank? A tank of 55 gallons (long) or up will be necessary to house a small group. Although this species will do well in most types of set-ups, the ideal would be to imitate its natural river habitat. Try going for a sandy substrate with river rocks, some driftwood, and sturdy plants like Java fern or Anubias.
- Tank Size: A single Siamese algae eater may do fine in a 30-gallon tank, but much larger tanks are recommended for groups. A 50- to 55-gallon freshwater aquarium with a tight-fitting lid is suitable for a single SAE.
- Water Parameters: They are quite hardy when it comes to water parameters and can be kept in temperatures between 68-80°F (20-27°C), pH of 6.0-8.0, and soft to hard water. Maintain high water quality in your Siamese algae eater tank by performing weekly water changes.
- Décor: Provide them with hardscape and other decor to graze and rest on. As a tropical species, it’s best to keep Siamese algae eaters in warm, lushly planted tanks. To mimic the natural habitat of Siamese algae eaters, aim for a neutral to slightly acidic pH. Though Siamese algae eaters can often be found in rivers and streams in their native habitat, they would likely be slow-moving. The ideal setup for this species is a densely planted tank with moderate water flow. Avoid disturbing algae-growing surfaces as much as possible during cleaning.
- Water Quality: Fish that naturally inhabit fast-flowing rivers that continually receive fresh, clean and oxygenated water don't respond well to low water quality in the aquarium. The Siamese algae eater is no exception. Keep up with weekly water changes to ensure the tank stays clean. Regular water changes ensure optimal water quality by removing the byproducts of the nitrogen cycle that accumulate over time.
Diet and Feeding
With the word “algae eater” in the name, you should expect these fish to make effective members of an aquarium cleanup crew. Like Plecostomus, Siamese algae eaters have suckermouths which enable them to adhere to smooth surfaces in the tank. Many aquarium hobbyists find that Siamese algae eaters eat more algae as juveniles than they do as adults. This may be because they rely more on algae as a food source when they’re small. Once they grow up, the fish are better able to compete with their tankmates for other food sources. Another way to increase the efficacy of your Siamese algae eater is to keep more than one of them. Stock your tank appropriately according to its volume, however, and be mindful that these fish can become territorial as they mature.
Wild Siamese algae eaters are bottom feeders. They scour the river floor for detritus, microalgae, phytoplankton, and aufwuchs: basically any small, edible bits they can find. Although you'll still have to perform regular aquarium maintenance, they can help in keeping pesky algae like hair algae under control. Some will even nibble on black beard algae, an annoying type that barely any other fish will go for.
The Siamese algae eater is an omnivorous species is not picky and will happily consume both protein and plant matter - including flakes, wafers, freeze-dried foods, frozen fish food, and blanched vegetables. Its downturned, small mouth allows it to reach every nook and cranny when searching for small food particles, freshwater plankton, and of course algae that grows on surfaces. Because juveniles require a lot of nutrients to grow, they will forage nonstop for leftovers and all kinds of algae - including hair and black beard algae (BBA). As they reach adulthood, their hefty size allows them to get the lion’s share of the fish food, so they are less likely to graze on algae.
Read also: Walnut Keto Guide
Because the average home aquarium is too clean to sustain a group of Siamese algae eaters, you'll have to supplement their diet. Avoid protein-rich foods; daily meals of commercial herbivore food, algae tabs, spirulina, blanched leafy greens and the like are much better.
To ensure a balanced diet for Chinese Algae Eaters, provide algae wafers or fresh vegetables like peas, zucchini, and spinach. As they mature, supplement their diet with protein-rich foods such as bloodworms, daphnia, and other live or frozen foods.
Tank Mates
These fish are generally peaceful by nature, but they do like to have their own space. Avoid keeping this species with other territorial bottom-dwellers like red tail sharks. There’s little need to worry about fish that occupy other levels in your tank. Top- and middle-dwelling fish like tetras, swordtails, gouramis, and barbs are unlikely to bother your Siamese algae eater. Snails make peaceful tankmates for Siamese algae eaters and they may target different types of algae.
They can get along with other tank mates in a community setting, as long as you take their speed and bottomless stomachs into account. To make sure they don’t hog all the available food, pair them with similar-sized, fast-swimming species - such as loaches, barbs, giant danios, cichlids, and livebearers.
If you keep one alone, it may become skittish. This is a peaceful species, although it is quite active, so it's best not to keep it with timid fish that appreciate their peace and quiet. As for invertebrates, you should avoid small shrimp like Neocaridina. However, larger species like Amanos should be fine, as will dwarf crayfish.
Read also: Weight Loss with Low-FODMAP
Breeding
It's not common for Siamese algae eaters to breed in the home aquarium. In captivity, successful breeding is extremely rare and mostly accidental, so it is not well-documented where they lay their eggs. This doesn't necessarily mean the SAEs for sale in your local aquarium store are live-caught. The Siamese algae eater is a relatively popular aquarium fish, so you should be able to find it for sale or have it ordered in for you at most aquarium stores. You can also order your fish online.
Breeding Chinese Algae Eaters in a home aquarium is a rare and challenging feat. In the Far East, they are often bred successfully with the aid of hormone treatments, but such methods are typically not available to hobbyists. If you attempt to breed them naturally, you will need a lot of patience and some luck. Mimic their natural habitat by providing a well-planted tank with plenty of hiding spots. They are egg-layers, and the fry typically hatch within 2-3 days. Newly hatched fry will feed on algae and other small particles in the tank.
Sexing Chinese Algae Eaters can be challenging. Generally, females tend to have a rounder, fuller body shape compared to males, especially when they are ready to spawn. However, this is not a definitive method, as some males may also appear plump.