Green Borneo Hillstream Loach（Gastromyzon lepidogaster）（SUPER RARE!!!)

Green Borneo Hillstream Loach — A Super Rare Gem from the Rivers of Borneo

Extraordinary, alien-like, and breathtakingly rare, the Green Borneo Hillstream Loach (Gastromyzon lepidogaster) is one of the most coveted and unusual freshwater fish in the hobby. Endemic to the fast-flowing, crystal-clear hill streams of Borneo, this remarkable species has evolved a flattened, hydrodynamic body and powerful sucker-like underside to cling to rocks in powerful currents — a feat of natural engineering that makes it as fascinating to observe as it is beautiful to look at.

The Green Borneo Hillstream Loach displays a stunning mosaic of green, gold, and dark patterning across its flattened body — a living piece of natural art that glides effortlessly across rocks and glass. Exceptionally rare in the trade, this is a true collector’s species.

Care at a Glance

• Common Name: Green Borneo Hillstream Loach
• Scientific Name: Gastromyzon lepidogaster
• Origin: Borneo (fast-flowing hill streams)
• Adult Size: 2.5 – 3.8 cm (1 – 1.5 inches)
• pH: 6.6 – 7.5
• General Hardness (GH): 6 – 12
• Carbonate Hardness (KH): 1 – 2
• TDS: 100 – 300
• Temperature: 22 – 24°C (68 – 75°F) — cooler water is essential
• Temperament: Peaceful herbivore; non-aggressive
• Difficulty: Easy to Moderate
• Shrimp Safe: ✅ 100% shrimp safe!

Tank & Setup Tips

Hillstream loaches require high water oxygenation and strong flow — replicating the fast-moving hill streams of their native Borneo is essential for their long-term health. Use a powerful filter or powerhead to create strong surface agitation and current. Water temperature must be kept cool (22–24°C); they do not tolerate warm or stagnant water.

Aquascape with smooth river rocks, slate, and pebbles for them to graze on. A well-established tank with natural algae and biofilm growth on rocks and glass is ideal — this forms the bulk of their natural diet. Avoid fine sand substrates that may clog their feeding apparatus.

Feeding

Herbivorous grazers. They feed primarily on algae, biofilm, and aufwuchs (the microscopic organisms that grow on rock surfaces). Supplement with blanched vegetables (zucchini, cucumber, spinach), algae wafers, and spirulina-based foods. A mature tank with established algae growth is strongly recommended before introducing them.

Compatible Tank Mates

Peaceful and completely shrimp safe — an excellent addition to planted shrimp tanks with appropriate flow. Ideal tank mates include small, peaceful nano fish (ember tetras, chili rasboras, small danios), other hillstream loaches, and dwarf shrimp. Avoid large or boisterous fish that may stress them.

Breeding

Breeding in captivity is considered difficult and rarely achieved outside of specialist setups. Replicating the precise conditions of their native hill streams — including strong flow, cool temperatures, and pristine water quality — is required.

📸 Photos are for reference only. Actual fish may vary slightly in colour and pattern — each one is uniquely beautiful!