Tiger Hillstream Loach (Sewellia sp. 'Tiger')

The Tiger Hillstream Loach (Sewellia sp. 'Tiger') is a striking hillstream loach from fast-moving, highly oxygenated streams in Vietnam and surrounding Southeast Asian countries. Its flattened, hydrodynamic body is decorated with vivid black and creamy-yellow-white striping across its dorsal surface — the pattern giving it its common name. Males develop tubercles on the snout during breeding condition.

Hillstream loaches are highly specialized for life in torrential mountain streams, featuring a flat body shape, broad paired fins positioned horizontally, and a modified ventral surface that acts as an adhesive suction disk, allowing them to cling to smooth rocks and surfaces in powerful currents. In the aquarium, they require replication of these high-flow, high-oxygen conditions to thrive.

Tiger Hillstream Loaches are primarily algae and biofilm grazers, spending their time clinging to and grazing the surfaces of rocks, driftwood, and glass. They are peaceful with other fish but may compete with others of their own kind in small spaces — provide multiple flat rock 'territories' when keeping groups.

This species demands more specific care than typical community fish: very high water flow (10–15x tank volume per hour), excellent oxygenation, cool water, and algae/biofilm-covered surfaces. In the right setup, they are active, personable fish that are highly rewarding to keep.

Water Parameters: pH 6.5–7.5, temperature 20–24°C. Cool, highly oxygenated water is absolutely essential. Use powerheads, spray bars, and/or wavemakers to create strong, turbulent flow mimicking mountain streams. Avoid warm, low-oxygen conditions. GH 5–15.

Tank Setup: Minimum 80 liters with powerful flow (10–15x turnover). Use a substrate of smooth pebbles and river rocks, with large flat rocks for grazing and territory. Allow algae and biofilm to colonize surfaces — do NOT scrub all surfaces clean. Strong lighting promotes algae growth as natural food.

Feeding: Primarily algae and biofilm grazers. Supplement with sinking algae wafers, blanched vegetables (zucchini, cucumber), and spirulina-based sinking foods. Occasional frozen foods like micro bloodworm are acceptable. Feed sparingly of prepared foods to encourage natural grazing.

Tankmates: Compatible with other fast-water species: danios, hillstream barbs, White Cloud Mountain Minnows, and similar cool-water tolerant fish. Avoid tropical fish requiring warm, still water. Keep multiple Tiger Hillstream Loaches with sufficient flat rock territories to reduce competition.

Health: Sensitive to warm, still, or low-oxygen water — these conditions rapidly cause stress and death. Maintain cold, powerful flow consistently. Monitor for bacterial infections and ich.