The Hillstream Loach (Sewellia lineolata) is a unique freshwater fish adapted to fast-flowing, oxygen-rich streams. It has a flattened body and strong suction-cup-like fins, allowing it to cling to rocks and substrate in high-current environments. Peaceful and active, it is ideal for aquariums with strong water flow and plenty of hiding spots.
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The Hillstream Loach (Sewellia lineolata) is a unique freshwater fish adapted to fast-flowing, oxygen-rich streams. It has a flattened body and strong suction-cup-like fins, allowing it to cling to rocks and substrate in high-current environments. Peaceful and active, it is ideal for aquariums with strong water flow and plenty of hiding spots.
Flattened, elongated body adapted for clinging to rocks. Brown to gray base coloration with intricate patterned markings. Strong suction-cup-like fins for attaching to surfaces in strong currents. Adults reach 2–3 inches. Small mouth positioned ventrally for grazing.
5–8 years with proper care
Primarily herbivorous; feeds on biofilm, algae, and micro-organisms on rocks and substrate. Can be supplemented with algae wafers, blanched vegetables (spinach, zucchini), and occasional protein-based foods like bloodworms or daphnia.
Hillstream Loaches are fascinating, functional, and decorative bottom dwellers for aquariums with strong currents and high oxygen levels. Their grazing behavior helps control algae, and their unique appearance adds natural beauty to the tank.
Moderate to Advanced – requires strong water flow, high oxygenation, smooth surfaces, and stable water parameters.
20+ gallons with strong flow
6.5 to 7.5
5–12 dGH
68–75°F (20–24°C)
2–3 inches
Small, peaceful fish such as rasboras, danios, and small tetras. Avoid large or aggressive tankmates.
Aggressive or very large fish that may outcompete them for food or harass them. Avoid slow-moving or delicate species that may be stressed by the current.
Sewellia lineolata
Balitoridae
Southeast Asia – China, Vietnam, Thailand; fast-flowing streams and rivers with rocky substrates.
Peaceful; can be kept in small groups. Non-aggressive and compatible with other calm species.
Feed multiple times daily with algae wafers, blanched vegetables (spinach, zucchini), and occasional protein foods like bloodworms or daphnia. Ensure food is available on surfaces they can graze.
Breeding in captivity is very challenging and rarely documented. They scatter eggs on rocks or substrates, with no parental care. Specialized flow and oxygen-rich conditions are needed.
pH: 6.5–7.5, Temperature: 68–75°F (20–24°C), Hardness: 5–12 dGH, Ammonia/Nitrite: 0 ppm, Nitrate: <20 ppm
Sensitive to poor water quality and low oxygen. Prone to stress and infections if flow is inadequate. Maintain high water quality and strong current.
Peaceful, active during the day, and excellent for community tanks. Prefers strong water currents and plenty of oxygen. Often seen clinging to rocks, stones, or driftwood, grazing on biofilm.
Native to fast-flowing rivers and streams in Southeast Asia, particularly China, Vietnam, and Thailand. Adults reach 2–3 inches. Hillstream Loaches require a tank with high oxygenation, moderate to strong water flow, and smooth rocks or stones for grazing. A varied diet of biofilm, algae, and supplemental foods promotes health, vibrant coloration, and natural behavior. They are excellent for adding interest and algae control in high-flow aquariums.