Reticulated Hillstream Loach - Sewellia lineolata

Common Name: Reticulated Hillstream Loach / Vietnamese Hillstream Loach
Scientific Name: Sewellia lineolata
Native Region: Vietnam – Central Vietnam, Mekong drainage
Origin: Tank Raised - PA
Adult Size: Approximately 2–2.5"
Temperament: Peaceful / Social
Diet: Omnivore / Aufwuchs Grazer
Currently Feeding On: EBO Spirulina Tabs, EBO Spirulina Softgran, EBO Artemia softgran
Swimming Level: Bottom / Rock Surfaces
Recommended Group: 4+

The Reticulated Hillstream Loach is one of the most recognizable and attractive hillstream loaches available to aquarists. Its flattened body, broad pectoral and pelvic fins, and intricate dark reticulated pattern allow it to cling tightly to rocks and other hard surfaces in strong current. The contrasting lines and geometric markings make this species especially striking when viewed against light-colored stone.

In nature, Sewellia lineolata inhabits shallow, fast-flowing streams and riffles in central Vietnam. These environments typically feature clear, highly oxygenated water flowing over bedrock, cobble, gravel, and smooth stones. The strong current and abundant sunlight encourage the growth of algae, diatoms, and other periphyton that form an important part of the loach's natural food supply.

Reticulated Hillstream Loaches are peaceful community fish and are generally best kept in groups. They spend much of their time moving across rocks and other surfaces while searching for biofilm and small food organisms. Males may display mild territorial behavior toward one another, but providing plenty of rock surfaces and visual breaks helps distribute interactions. Their peaceful nature makes them excellent inhabitants of appropriately designed hillstream and peaceful community aquariums.

Care Requirements

Temperature: 68–75°F
pH: 6.5–7.5
Tank Size: 30 gallons or larger
Water: Clean, highly oxygenated, with strong circulation
Group Size: 4+

A mature aquarium with strong water movement is essential for Sewellia lineolata. Multiple powerheads, an oversized filter, or a dedicated river-style circulation system can be used to create the turbulent flow these fish naturally experience. The aquarium should contain plenty of smooth rocks, rounded cobbles, and other hard surfaces where natural biofilm can develop.

Bright lighting is beneficial because it encourages algae and biofilm growth on the rocks. A thin layer of fine gravel or sand can be used around the rockwork, while open areas should be left for the loaches to move between feeding surfaces. Driftwood can be included, although smooth stone should make up a significant portion of the habitat.

Their natural diet consists largely of algae, periphyton, detritus, and small benthic invertebrates. Fish should be offered a steady supply of algae- and vegetable-based foods along with supplemental protein. EBO Spirulina Tabs and EBO Spirulina Softgran are excellent staples, while EBO Artemia Softgran and other protein-rich foods can provide additional variety. Because these fish constantly graze, it is especially important that the aquarium itself develops a healthy layer of natural biofilm rather than relying exclusively on prepared foods.

Excellent water quality is critical. Strong aeration, high dissolved oxygen, regular water changes, and effective mechanical and biological filtration should be considered essential rather than optional. Avoid keeping these loaches in warm, stagnant aquariums where oxygen levels can become inadequate.

Reticulated Hillstream Loaches are ideal companions for other peaceful fish that appreciate clean, well-oxygenated water and cooler temperatures. Small danios, rasboras, peaceful barbs, and other compatible stream-dwelling species can work well. Avoid aggressive or excessively warm-water species, as well as tankmates that will monopolize food from the bottom.

Difficulty: Moderate
Breeding: Egg Scatterer

Why We Like Them

• One of the most distinctive hillstream loaches

• Incredible reticulated body pattern

• Specialized flattened body and sucker-like fins

• Fascinating behavior on rocks and glass

• Excellent algae and biofilm grazer

• Peaceful and well suited to community aquariums

• Perfect centerpiece for a river-style aquarium

• Fascinating species for aquarists interested in specialized stream fish

All livestock is carefully quarantined and monitored before being offered for sale at Saburai Aquatics.