Reticulated Hillstream Loach (1.75-2”)

Scientific Name

• Sewellia lineolata*

Maximum Size and Lifespan

• Size: Around 2.5–3 inches (6–7.5 cm)

• Lifespan: Typically 8–10 years with proper care

Recommended Aquarium Size, Water Changes, and Care

• Tank Size: A minimum of 20–30 gallons for a small group (larger tanks preferred for stable water and multiple individuals).

• Water Parameters:

  • Temperature: 68–75°F (20–24°C)

  • pH: 6.5–7.5
    

• Water Movement & Oxygen: Extremely high. They require fast-flowing, well-oxygenated water that mimics streams and rivers. A strong powerhead or river-tank manifold setup is highly recommended.

• Water Changes: Weekly water changes of 30–50% help maintain pristine water and high oxygen levels.

• Substrate & Decor: Smooth rocks, cobbles, and driftwood to graze on algae. Sand or fine gravel substrate. Ensure plenty of flat surfaces for resting and grazing.

Tankmates

• Peaceful community species that thrive with other non-aggressive fish.

• Suitable companions: White Cloud Mountain Minnows, Danios, small Rasboras, other loaches adapted to similar conditions. Dwarf cichlids like apistos and rams, rainbow shiners.

• Avoid aggressive, territorial, or slow-moving fish that dislike strong currents.

Diet

• Primarily grazers of algae and biofilm on rocks.

• Supplement with:

  • Sinking algae and protein enriched wafers

  • Blanched vegetables (zucchini, green beans, cucumber)

  • Frozen bloodworms and brine shrimp

• A mature, algae-rich tank is ideal to support natural grazing behavior.

Overview

The Reticulated Hillstream Loach is a striking freshwater species known for its flattened, ray-like body and intricate reticulated patterns. Its streamlined shape and sucker-like fins allow it to cling to rocks in strong currents, resembling miniature stingrays. They are highly active grazers, thriving in fast-moving, oxygen-rich aquariums with clean water and plenty of algae growth. While peaceful and social, they should be kept in groups for natural behavior but require aquarists to replicate their specialized riverine habitat.

Natural Environment

Native to fast-flowing rivers and streams of Vietnam and Laos, Sewellia lineolata inhabits shallow, rocky areas with strong currents, high oxygen levels, and abundant algal growth. Their natural environment is rich in smooth stones, boulders, and crevices, where they graze continuously and use their modified fins to hold position against the flow.

Breeding

Breeding in aquaria is possible but challenging:

• Spawning Setup: Provide a mature, well-oxygenated aquarium with strong current and plenty of smooth stones.

• Behavior: Males establish small territories on flat surfaces. During courtship, they display to females and guide them under stones or into crevices.

• Eggs: The female deposits eggs beneath rocks, where the male fertilizes them. Eggs typically hatch in 7–10 days.

• Raising Fry: Fry are small and require infusoria, biofilm, or powdered fry food. A well-established tank with natural microfauna greatly improves survival rates.