Hillstream Loach (Sewellia lineolata)

The Hillstream Loach is a unique and fascinating freshwater fish known for its flattened body, beautiful spotted and striped patterns, and ability to cling to rocks and aquarium glass. Often called the Butterfly Loach or Reticulated Hillstream Loach, this peaceful species is native to fast-flowing streams in Southeast Asia.

Hillstream Loaches are excellent additions to mature freshwater aquariums with strong water movement and high oxygen levels. Their unusual appearance and entertaining grazing behavior make them a favorite among aquarists looking for something different.

Care Requirements

• Scientific Name: Sewellia lineolata
• Common Names: Hillstream Loach, Reticulated Hillstream Loach, Butterfly Loach
• Origin: Vietnam
• Care Level: Intermediate
• Temperament: Peaceful, occasionally territorial with other hillstream loaches
• Maximum Size: 2.5–3 inches
• Minimum Tank Size: 30 gallons
• Temperature: 68–76°F
• pH: 6.5–7.5
• Diet: Omnivore, primarily algae and biofilm grazer
• Lifespan: 5–10 years
• Group Size: Best kept in groups of 3 or more with adequate space

Diet & Feeding

Hillstream Loaches spend much of their time grazing on algae, biofilm, and microorganisms growing on rocks, driftwood, and aquarium surfaces.

While they naturally consume algae, they should also receive a varied diet of high-quality sinking foods, algae wafers, spirulina-based foods, and occasional frozen or live foods such as bloodworms and brine shrimp.

A mature aquarium with established biofilm is especially beneficial for their health. Hillstream Loaches should not be expected to survive on algae alone.

Tank Setup & Compatibility

Hillstream Loaches thrive in aquariums that replicate their natural fast-flowing stream habitats. Provide smooth rocks, driftwood, and plenty of surfaces for algae and biofilm growth.

Strong filtration, moderate to high water movement, and excellent oxygenation are essential for keeping these fish healthy.

A sand or smooth gravel substrate works well, along with rounded river stones and open areas for grazing.

Hillstream Loaches are generally peaceful and can be housed with other non-aggressive fish that enjoy similar water conditions. Suitable tank mates include White Cloud Mountain Minnows, certain danios, and other peaceful stream-dwelling species.

Avoid aggressive fish or species that require consistently warm water.

Important Information

Hillstream Loaches are often purchased for algae control, but they require specialized conditions to thrive. They are not traditional tropical algae eaters and generally prefer cooler, highly oxygenated water.

Their flattened bodies and specialized fins allow them to cling to surfaces in strong currents, making them fascinating to observe.

Although peaceful, males may occasionally display territorial behavior toward one another, especially around preferred feeding areas.

For the best results, provide a mature aquarium with strong water movement, high oxygen levels, smooth rocks, and a consistent food supply.

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