Reticulated Hillstream Loach - Sewellia lineolata

Reticulated Hillstream Loach (Sewellia lineolata)

The Reticulated Hillstream Loach is a fascinating freshwater loach, prized for its flattened body shape, strong clinging fins and beautiful maze-like reticulated patterning. Also known as the Tiger Hillstream Loach or Gold Ring Butterfly Sucker, this species is adapted for life in cool, fast-flowing, highly oxygenated streams. In the aquarium it is a peaceful and active grazer, best suited to a mature river-style setup with smooth rocks, strong oxygenation and plenty of natural biofilm.

Common Name:
Reticulated Hillstream Loach. Also commonly referred to as the Tiger Hillstream Loach, Hillstream Loach, Gold Ring Hillstream Loach, Gold Ring Butterfly Sucker or Butterfly Loach.

Scientific Name (Latin):
Sewellia lineolata

Maximum Size:
Around 5–6 cm in captivity, making it a small but specialist bottom-dwelling loach.

Water Type:
Freshwater

Origin / Natural Habitat:
Native to Southeast Asia, especially Vietnam and Laos. In the wild, it is associated with fast-flowing hill streams, rapids and shallow rocky waterways with clean, highly oxygenated water. It spends much of its time attached to stones and other hard surfaces while grazing through algae, biofilm and small invertebrates.

Water Parameters:
Temperature: 20–24°C
pH Range: 6.5–7.8
Hardness: soft to moderately hard water

Temperament:
Generally peaceful and non-aggressive with other fish, but it is a specialist species because of its environmental needs. It should not be kept with large, aggressive or very boisterous tank mates that may outcompete it or disturb it constantly.

Diet:
Omnivorous grazer. It should be offered a varied diet including algae wafers, spirulina-based foods, fine sinking foods, catfish pellets, blanched vegetables and small frozen foods such as daphnia, cyclops, brineshrimp and bloodworm. It also benefits greatly from natural algae and biofilm growth within a mature aquarium.

Minimum Tank Size:
A practical recommendation is at least 80 litres for a small group, with a longer aquarium preferred to provide strong flow, open grazing areas and enough surface space for each fish.

Behaviour & Activity:
This is an active bottom and surface-grazing loach that spends much of the day attached to smooth rocks, glass, wood and décor. It is more visible than many loaches and can be active during the daytime when settled. Best kept in a group of at least 4–6, where natural grazing, displaying and social behaviour can be observed. A secure lid is recommended, as hillstream loaches can climb glass and may escape from open aquariums.

Aquarium Category:
Community Fish
This species is peaceful enough for a suitable community aquarium, but it should be kept with fish that enjoy similar cooler, clean, oxygen-rich conditions. Suitable tank mates include White Cloud Mountain Minnows, small danios, peaceful hillstream loaches, small gobies, temperate rasboras and other calm current-loving species. Avoid warm tropical community tanks, goldfish systems with poor water quality, aggressive bottom-dwellers, large predators and low-flow aquariums.

Special Requirements or Care Notes:
This fish needs a mature river-style aquarium with strong oxygenation, excellent filtration and regular maintenance. Smooth rocks, cobbles, bright lighting for algae growth, open grazing surfaces and extra water movement are strongly recommended. It should not be added to brand-new, sterile or poorly oxygenated aquariums. Higher temperatures reduce oxygen levels and can cause stress, so cooler, well-aerated water is much safer for long-term health.

Suitable for:
Intermediate fishkeepers

Availability:
Occasional in trade

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Please note that Mother Nature is a wonderful thing, and variation in patterns and colours will occur — that is part of the unique beauty of these animals.