Borneo hillstream loach

Care at a glance

Overview

The Borneo hillstream loach is a tiny, flattened grazer that lives its whole life clinging to hard surfaces and picking at the film of algae that grows there. It is social, so keep a group of six or more and they will spread across the rocks and glass, feeding and interacting through the day. It is completely peaceful and suits cool, fast-water tankmates like other hillstream loaches and small danios. A mature tank with plenty of algae is important, and this should be topped up with sinking wafers, biofilm blocks, and small frozen foods. Give a group a well-oxygenated tank of around 75 liters or more with strong flow.

In the wild

Gastromyzon ctenocephalus is found only in Borneo, where it lives in shallow, fast-flowing forest streams that tumble over rock and gravel. The water is cool and highly oxygenated, usually 20 to 24 C, and sits from slightly acidic to neutral at about pH 6 to 7.5. This is a demanding habitat to recreate: use a powerhead or strong filter return to keep the current brisk, add smooth stones and cobbles for grazing, and keep temperatures down. Steady oxygen and pristine, well-filtered water matter far more to this fish than plants or decor.

Good to know

Gastromyzon ctenocephalus belongs to Gastromyzontidae, the hillstream loach family. It is a small species, growing to only about 4 cm, with a low, flattened body and broad paired fins that fuse into a suction pad, letting it hold station on rocks in a ripping current. Unlike the botiid loaches it has no spine below the eye. Breeding is not recorded in aquaria, and it is thought to scatter eggs among stones and gravel in fast water, with the fish in shops collected from the wild.

Did you know

The suction hold of a hillstream loach comes from its flattened underside and fused paired fins, which work together like a living limpet foot. This lets Gastromyzon graze in currents strong enough to sweep most fish off the rocks.

Related species

• Spotted hillstream loach

  Gastromyzon punctulatus

  2.6 in (6.5 cm)20 gal (75 L)68–75°F (20–24°C)

• 

  Tiger hillstream loach

  Sewellia lineolata

  2.6 in (6.5 cm)25 gal (95 L)68–75°F (20–24°C)

• 

  Butterfly Loach

  Beaufortia kweichowensis

  3 in (7.5 cm)25 gal (95 L)61–75°F (16–24°C)
• Chinese butterfly loach

  Pseudogastromyzon cheni

  2.4 in (6 cm)20 gal (75 L)64–75°F (18–24°C)
• Panda loach

  Yaoshania pachychilus

  2.8 in (7 cm)20 gal (75 L)64–75°F (18–24°C)

• 

  Red hillstream loach

  Beaufortia leveretti

  3.1 in (8 cm)24 gal (90 L)64–75°F (18–24°C)