Gastromyzon farragus – Borneo Sucker
Gastromyzon farragus was first described in 2006 by H. H. Tan and M. U. C. Leh. The Dutch name used for this species is Borneo Steenkruiper. They are part of the family of Hillstream Loaches (Gastromyzontidae).
The genus name Gastromyzon is derived from the Greek words ‘gaster’ (belly) and ‘myzo’ (to suck), referring to the suction disc formed by enlarged pectoral fins, flaps above the pelvic fins, and fused pelvic fins. The species name farragus comes from Latin and means ‘mixture’, referring to the color pattern of this species, which consists of stripes on the back and spots on the flanks.
Description
The Gastromyzon farragus, also known as the Borneo Sucker, is a small fish with a maximum standard length of approximately 3.5 to 4.0 centimeters, giving it a total length of around 5 centimeters. Its body shape is adapted to life in fast-flowing water, with a flattened underside and enlarged fins that form a suction disc.
The color of Gastromyzon farragus is predominantly dark brown. The back has 9 to 10 thin, cream-colored transverse bands, while the flanks (sides) are covered with spots and irregular patterns. The back of the head is brown with cream-colored spots. The tail fin is red in color in living animals. There are no scales on the belly.
In terms of gender differences, adult females are noticeably heavier and often slightly larger than males. This difference is most noticeable when viewing the fish from above or below.
They are described as peaceful, but their specific environmental requirements limit the choice of suitable aquarium companions. In nature, they usually position themselves with their heads against the current, often along the sides, behind or under rocks, where their specialized physique allows them to search for food and maintain their position without being washed away. They can be somewhat territorial, with some individuals defending their space, often a good feeding spot, more than others.
The swimming zone of this fish is mainly the bottom and lower water layers, where they attach themselves to surfaces in fast-flowing water.
Biotope
Gastromyzon farragus is a species endemic to Borneo. Its distribution is limited to the tributaries of the Sadong River system in the south of the state of Sarawak, Malaysian Borneo. The type locality is in the Samarahan Division, near Serian, in the Sadong River basin.
These fish are strictly inhabitants of fast-flowing, shallow streams with clear, oxygen-rich water. They have been found from sea level to elevations of 1350 meters above sea level in the hilly areas of Borneo. They typically inhabit rapids and parts of the stream where the water flows rapidly, and are often found above or below cascades and waterfalls.
The substrate in their natural habitat generally consists of gravel, rocks, boulders, or rocky bottoms covered with a rich biofilm of algae and other microorganisms. Aquatic plants are uncommon in their habitat, although riparian vegetation may be present. These fish are most abundant in partially or fully shaded areas.
Diet
In their natural habitat, the diet of Gastromyzon farragus consists mainly of benthic algae and associated microorganisms scraped from hard surfaces. They are found in fast-flowing streams where algae and biofilms are abundant on rocks and other substrates.
In captivity, they accept good quality food, including dried feeds and meatier options such as live or frozen mosquito larvae. However, it is important to avoid diets that are too high in protein, as this can cause internal problems.
Practical tips for feeding in the aquarium include offering homemade foods with a mix of natural ingredients, such as fresh vegetables and Spirulina, bound with gelatin. This makes it possible to create a diet rich in vegetables. For long-term success, a mature aquarium with an abundant supply of algae-covered rocks and other surfaces is essential.
If there is insufficient algae to grow in the main aquarium, or if there are many herbivorous fish that quickly consume the available algae, it may be necessary to maintain a separate “breeding aquarium” to grow algae on rocks. These rocks can then be cyclically exchanged with those in the main aquarium. This breeding aquarium does not need to be large and only requires strong lighting; in sunny climates, it can even be kept outdoors. Diatoms and softer, green algae species are preferred over harder species such as black beard algae.
A common mistake is keeping these fish in an biologically immature aquarium, which can lead to health problems. Feeding them a diet that is too rich in protein should also be avoided. It is important to know that Gastromyzon farragus and related species are often sold in a weakened condition, which can be difficult to correct. A good dealer will have already done something about this before the sale, but if you buy weakened specimens, they will initially need a constant source of suitable food, without competition from other fish, in order to recover.
The Aquarium
For a group of these fish, an aquarium with a minimum bottom size of 60 by 30 centimeters is recommended. Set up the aquarium with a mixture of gravel and sand on the bottom. It is important to add water-polished stones and pebbles of various sizes. Older pieces of driftwood can also be used, but avoid new pieces that may release tannins and affect water quality.
Although aquatic plants are not typical of their natural habitat, hardy species such as Microsorum, Crinum, and Anubias spp. can be used. These plants can attract algae, which provides a food source, and offer additional hiding places. Adding dry oak or beech leaves is also recommended, as these become covered with algae.
Rocks and stones, especially those that have been smoothed by water, are important for providing shelter and surfaces for algae growth. Although shelter is important, open space is also needed for flow and movement.
A temperature of 20–24°C is recommended, but they can tolerate higher temperatures (up to 27°C, and even 30°C for short periods) provided that oxygen levels remain high. Keep the pH between 6.0 and 7.5.
The water must be clean and well oxygenated. A powerful filter with a flow rate of 4-5 times the aquarium volume per hour is a minimum requirement. Additional powerheads and air stones may be necessary to ensure the required flow and aeration.
Because these fish feed on biofilm and require stable water conditions, they should never be placed in an aquarium that is not biologically mature. A well-fitting lid is necessary because they can climb up the glass
Suitable and unsuitable tankmates
Suitable: Small, pelagic cyprinids such as Tanichthys, Danio, and Rasbora. Riverine gobies from the genera Rhinogobius, Sicyopterus, and Stiphodon. Crayfish such as Glyptothorax, Akysis, and Hara spp. Some catfish from the families Nemacheilidae, Balitoridae, and Gastromyzontidae may also be suitable, provided they are well researched. It is recommended to keep a group of 4 or more of these fish in order to observe their behavior.
Unsuitable: Larger, aggressive, territorial, or otherwise competitive fish.
Breeding Gastromyzon farragus
Breeding Gastromyzon farragus in captivity has not been successful to date, and there are no documented cases of successful breeding in aquariums.
Conclusion
Gastromyzon farragus, or Borneo Sucker, is a unique fish that specializes in living in fast-flowing, oxygen-rich streams on Borneo. With its flattened body and suction disc, it can attach itself firmly to rocks to eat algae and biofilms. These specific habitat requirements make it a challenging but fascinating species for the experienced aquarium keeper.
Keeping the Borneo Sucker requires a well-equipped aquarium with strong currents, plenty of hiding places, and an abundance of algae. Although breeding in captivity has not yet been successfully documented, observing these peaceful fish in a suitable environment is a great pleasure. Their need for stable, clean water conditions and a diet that includes algae emphasizes the importance of a biologically mature aquarium and careful selection of tank mates.
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Author
Since I bought my first second-hand aquarium when I was twelve, I have always had one or more aquariums. I even converted a garage into a breeding room where I had 50 aquariums containing around 10,000 liters of water. At the moment, I have two aquariums: a 1,250-liter Tanganyika aquarium and a 250-liter community aquarium with plants. For the past 10 years, I have been working on this website as a writer and photographer.
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