Blue Dorsal Borneo Sucker (Gastromyzon Ctenocephalus)

Rare Blue Dorsal Borneo Sucker (Gastromyzon ctenocephalus) — a stunning hillstream loach with vivid blue dorsal fins, perfect for fast-flowing, well-oxygenated aquaria.

• Overview: The Blue Dorsal Borneo Sucker, scientifically known as Gastromyzon ctenocephalus, is a highly sought-after species within the freshwater aquarium hobby. Native to the clear, fast-flowing streams and rivers of Borneo, this remarkable loach is prized for its striking appearance — a sleek, flattened body adorned with intricate mottled patterns in earthy browns and creams, and most notably, a brilliant cobalt-blue dorsal fin that catches the light beautifully. Its unique, sucker-like mouth and pelvic fins allow it to cling effortlessly to smooth rocks and driftwood, mimicking the natural habitats from which it originates. This species remains relatively uncommon in the trade, making it a genuine treasure for aquascapers and specialist keepers looking to add an authentic piece of the Southeast Asian riverine ecosystem to their collection.
• Water Conditions: The Blue Dorsal Borneo Sucker hails from swift, oxygen-rich mountain streams, so replicating these conditions is essential for its long-term health. A mature aquarium with strong, laminar water flow is non-negotiable — ideally produced by a powerhead or wavemaker to simulate the torrential currents of its native habitat. Water temperature should be maintained between 22°C and 26°C (72°F – 79°F), with a pH range of 6.5 to 7.5 and soft to moderately hard water (4–12 dGH). Excellent biological filtration, regular water changes of 30–50% weekly, and high dissolved oxygen levels are paramount. These fish are highly sensitive to poor water quality and elevated nitrates, so a pristine environment is critical. Substrate should consist of smooth river stones, cobbles, and fine sand, while large pieces of driftwood and broad-leafed plants (such as Anubias or Java Fern) provide resting zones and biological surface area.
• Tank Mates: When selecting tank mates, it is crucial to choose peaceful, non-competitive species that share similar water parameters and flow preferences. Ideal companions include other hillstream loaches such as Sewellia or Beaufortia species, as well as small danios, rasboras, or white cloud mountain minnows that relish brisk currents. Avoid large, boisterous, or territorial fish that may outcompete the Borneo Sucker for food or harass it. Similarly, avoid slow-moving, long-finned species that could be stressed by the strong water flow. Since Gastromyzon ctenocephalus is a gregarious species, keeping them in small groups of at least 4–6 individuals is strongly recommended; this reduces stress, encourages natural social behaviours, and creates a stunning visual display as they graze over rocks and glass alike. Do not keep them with aggressive cichlids, large catfish, or any fish that may view them as prey.
• Feeding Habits: In the wild, this species is a biofilm grazer, constantly rasping away at algae, diatoms, and the microscopic organisms that colonise riverbed surfaces. In the aquarium, they require a consistent and varied diet to thrive. Offer high-quality sinking wafers and algae tablets as a staple, alongside blanched vegetables such as cucumber, courgette (zucchini), and spinach, which should be anchored to the substrate or a feeding dish. Supplement their diet with frozen foods like bloodworms, brine shrimp, and daphnia, as well as finely crushed flake or pellet food. Because they have fast metabolisms, feed small amounts two to three times daily, ensuring food reaches the bottom before any quick-swimming tank mates intercept it. It is also beneficial to allow natural algae to grow on rocks and glass, as this provides a continuous, nutritious grazing source that mimics their wild feeding behaviour.
• Care Requirements: The Blue Dorsal Borneo Sucker is not a beginner fish; it demands dedicated, informed care and a tank that has been established for at least several months. A minimum tank volume of 30 gallons is recommended to provide ample swimming space, stable water chemistry, and room for multiple resting territories. Before introduction, acclimate them slowly via drip acclimatisation over 45–60 minutes, as they are extremely sensitive to sudden pH, temperature, and osmolarity shifts. Weekly maintenance should include substrate vacuuming, filter cleaning, and a partial water change with temperature-matched, dechlorinated water. Observe them daily for signs of stress, such as rapid breathing, clamped fins, or loss of appetite — these can indicate inadequate oxygenation or water quality issues. With proper care, this species can live for 5–8 years, rewarding the dedicated aquarist with a captivating display of natural riverine behaviour. Ensure the aquarium is tightly covered, as loaches are known to explore outside the waterline on occasion.
• Additional Notes: This species is best showcased in a biotope-style aquascape, with smooth rounded stones, gentle sand patches, and minimal planting to reflect their native Bornean streams. Strong lighting encourages algae growth, which is beneficial for grazing. Avoid copper-based medications, as they are lethally toxic to loaches. Always quarantine new arrivals for at least 2 weeks before adding them to a display tank to prevent the introduction of disease. Sourcing this species from reputable, ethical suppliers like ourselves ensures healthy, well-conditioned specimens that are acclimated to captive diets.