The Hillstream Loach (most commonly Sewellia lineolata or the Reticulated Hillstream Loach) is a small, unique freshwater fish famous for its miniature stingray-like appearance and excellent ability to graze on aquarium biofilm

Key Characteristics:

• Physical Adaptation: Their bodies are highly flattened, and their enlarged pectoral and pelvic fins act as a powerful suction cup. This allows them to anchor seamlessly to smooth rocks in raging river torrents.
• Behavior: They are peaceful, bottom-dwelling community fish. Males will occasionally engage in harmless, circular “fights” to assert dominance over territory or food.
• Size & Lifespan: They generally reach an adult size of 6–7 cm and can live between 5 to 8 years under the right conditions.

Specialized Tank Requirements:

Because they originate from fast-flowing, turbulent streams across Asia, they cannot be treated like standard tropical fish.

• Water Flow & Oxygenation: High water movement is non-negotiable. They require strong filtration, heavy surface agitation, or additional powerheads to replicate a river current and keep oxygen saturation high.
• Temperature: They prefer cooler conditions than most tropical setups. The ideal range is 20–25°C.
• Tank Setup: Provide a mature tank decorated with plenty of smooth river stones and driftwood. These surfaces are essential for them to cling to and graze on.
• Social Structure: Keep them singly or in groups of 3 or more. Keeping exactly two often results in the stronger individual bullying the weaker one.

Diet and Feeding:

While often sold to control algae, they are specifically aufwuchs (biofilm and micro-organism) grazers rather than true algae eaters. They can easily starve in a pristine, newly set up aquarium.

• Primary Diet: Natural biofilm and soft diatom algae growing on smooth rocks or glass.
• Supplements: High-quality sinking algae wafers, gel foods (such as Repashy), and blanched vegetables (zucchini, cucumber, spinach).
• Protein Variety: Occasional treats of frozen daphnia, brine shrimp, or bloodworms.