Add a truly unique oddball fish to your freshwater aquarium setup! The Reticulated Hillstream Loach (Sewellia lineolata)—also popular in the hobby as the Tiger Hillstream Loach or Butterfly Sucker—looks remarkably like a prehistoric miniature stingray. With a highly hydrodynamic, flattened body covered in a gorgeous, intricate gold-and-black reticulated pattern, this fascinating bottom-dweller spends its days fluttering across glass and crawling side-to-side on river rocks.

Beyond its striking appearance, it is a peaceful, hard-working addition to your cleanup crew that will actively graze on algae and biofilm throughout your tank.

Quick Care & Tank Parameters

• Scientific Name: Sewellia lineolata

• Common Names: Reticulated Hillstream Loach, Tiger Hillstream Loach, Butterfly Algae Eater, Chinese Sucker

• Adult Size: 2 to 3 inches (5 to 7.5 cm)

• Life Expectancy: 6 to 10 years

• Minimum Tank Size: 30 Gallons (for a small group)

• Water Temperature: 68°F to 75°F (20°C to 24°C) — Prefers cooler, sub-tropical water

• pH Range: 6.5 to 7.8

• Water Hardness: 4 to 15 dGH (Soft to Medium-Hard)

Key Features & Comprehensive Care Guide

Place of Origin & Natural Habitat

The Reticulated Hillstream Loach is native to the clean, clear, fast-flowing mountain streams, river rapids, and shallow riffles of Southeast Asia, primarily within Vietnam, Laos, and Cambodia. Their specialized horizontal pectoral and pelvic fins act like a natural suction cup, allowing them to grip tightly to smooth stones in heavy currents that would easily sweep other fish away.

Tank Size & Environment Setup

While these are small fish, they have strict environmental needs. A minimum tank size of 30 gallons (ideally a "long" tank footprint) is necessary to keep a proper social group.

To keep your Hillstream Loaches thriving, your aquarium aquascape should mimic a natural river biotope:

• High Flow & Oxygenation: This is non-negotiable. They require highly oxygenated water with strong surface agitation. Utilize heavy-duty canister filters, powerheads, or wavemakers to create high-flow river currents.

• Smooth Hardscape: Fill the tank with smooth river stones, flat pebble slabs, and pieces of driftwood. Avoid sharp rocks or jagged substrate that could scratch their scaleless undersides.

• Lighting: Moderate to high lighting is recommended because it encourages the growth of natural algae and healthy biofilm on your rocks—the loach's favorite grazing fields.

• Secure Lid: These fish are natural-born climbers and can easily slide up the glass or into filter intakes. A tight-fitting lid is an absolute must!

Feeding & Diet

Reticulated Hillstream Loaches are primarily specialized herbivores and biofilm grazers. They are fantastic for natural aquarium algae control, but they cannot survive on tank scraps alone.

• Daily Staples: High-quality sinking algae wafers, spirulina pellets, and gel-based foods.

• Occasional Protein: Frozen or live foods such as bloodworms, daphnia, and brine shrimp to supplement their diet.

• Fresh Veggies: They enjoy blanched zucchini, cucumber, or spinach weighed down on the tank floor.

Peaceful Tank Mates

Hillstream Loaches are exceptionally peaceful and reef-safe/shrimp-safe bottom dwellers. They do best in groups of 3 to 6+ of their own kind to minimize territorial stress.

• Ideal Choices: Look for other sub-tropical, current-loving, non-aggressive species. Excellent options include White Cloud Mountain Minnows, Danios (Zebra or Leopard), peaceful Barbs, Otocinclus Catfish, and Amano Shrimp.

• Species to Avoid: Avoid slow-moving, warm-water tropical fish like Bettas, Angelfish, and Discus. Also, avoid housing them with large, boisterous bottom-dwellers (like large Plecos) that will outcompete them for grazing space.

Breeding the Hillstream Loach

While considered a challenge, breeding Sewellia lineolata in a home aquarium is highly rewarding. To trigger breeding, house a mature group of 5 or more in a well-seasoned, algae-rich tank. Condition them with high-protein frozen foods and slightly increase the temperature by a few degrees to simulate spring rainfall. They will spawn in the gravel or crevices between smooth stones, and the tiny, free-swimming fry will emerge to feed on the microscopic biofilm coating your river rocks.

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