Golden Stripe Hillstream Loach (Gastromyzon cf. praestans)

Common Name

Golden Stripes Sucker, often sold simply as a Hillstream Loach. The cf. marker means the fish closely resembles Gastromyzon praestans, yet may be an undescribed or regional form that still needs taxonomic study.

Origin and Habitat

Native to Borneo hillstreams, collected from cool, crystal-clear tributaries where water races over bedrock, rounded cobble, and coarse gravel. These shallow riffles and runs have intense, steady current, very high oxygen, and bright light that grows a thin film of algae on rock plates. Aquatic plants are scarce in the fastest lanes; shelter comes from rocks, ledges, and gaps between stones, with leaf litter settling in calmer margins.

Temperature and Water Conditions

Aim for cool to mid-tropical water with vigorous aeration and strong, clean flow. A practical range is 20 to 24°C (68 to 75°F). Reports from similar habitats and successful aquaria place pH near neutral to slightly alkaline, about 6.5 to 7.8, with soft to moderate hardness. We do not recommend chasing or altering water parameters except for special breeding situations. Stable conditions, very high dissolved oxygen, and low nitrogen waste are far more important than exact numbers.

Appearance and Size

A compact, flattened river loach built for current. The body is chocolate to slate with bright golden stripes running lengthwise, and a fine pale tracery on the snout. Wide pectoral and pelvic fins act like suction pads on rock. Adults reach about 4 to 5 cm standard length (1.6 to 2.0 inches). Sexes look similar; males may show slightly broader heads and sharper color when in peak condition.

Diet in the Wild

A specialist periphyton grazer. It scrapes biofilm from stone and wood, taking diatoms, filamentous green algae, small amounts of cyanobacteria, and the tiny invertebrates that live within that film.

Feeding in Captivity

Success begins with seasoned rock. Allow smooth stones and slate to develop a green film under good light. Offer:

• Spirulina-rich wafers
• Algae-based micro pellets
• Gel foods pressed onto flat stones
• Small portions of frozen cyclops, daphnia, and spirulina-enriched baby brine shrimp as supplements, not as the main course

Place food directly on rock surfaces in the current so the fish can graze naturally.

Behavior and Tank Setup

Peaceful and best kept in a group so individuals can establish small rock-centered stations without stress. Use a long aquarium with a river-style manifold or added powerheads to create broad, even flow. Provide strong aeration, excellent mechanical and biological filtration, and frequent small water changes. Hardscape should be:

• Rounded cobble
• Slate plates
• Boulders with patches of fine sand or smooth gravel to protect the belly

Plants are optional; hardy rheophytes like Anubias, Microsorum, and mosses tied to rock do well along calmer edges. Ideal companions include:

• Danios
• White clouds
• Small rasboras
• Gentle rheophilic gobies that enjoy the same cool, fast water

Breeding

Home breeding is rarely documented for this form, yet behavior is presumed similar to other Gastromyzon. Courtship likely occurs on or between stones, with adhesive eggs placed in crevices, and no parental care. If you wish to try a project, think like a mountain stream:

• Keep flow brisk, oxygen near saturation, and water immaculate
• Build layered rock piles and include pockets of larger rounded gravel as a starting point, since these structures create natural gaps that shelter eggs from current and tank mates
• Allow biofilm to flourish so newly hatched fry find immediate micrograzing
• If eggs are found, move them gently to a small container with matching water and a fine bubble aimed across the clutch
• First foods are infusoria and quality fry powders, followed by newly hatched baby brine shrimp once fry are large enough

Quick Facts

• Scientific name: Gastromyzon cf. praestans
• Origin: Borneo hillstreams with clear, fast water
• Size: About 4 to 5 cm standard length (1.6 to 2.0 inches)
• Temperature: 20 to 24°C (68 to 75°F)
• pH: Commonly 6.5 to 7.8 in reports, stability is more important than exact value
• Temperament: Peaceful grazer, forms small rock-centered stations
• Diet: Periphyton grazer that consumes algae, diatoms, and micro-invertebrates
• Breeding: Rarely documented in aquaria, presumed crevice spawner without parental care

Tropical Fish Co. Notes

This little loach makes a river tank feel alive. When the stones are green and the flow hums, the gold stripes flash as the fish surf the current like tiny hovercraft. Think oxygen first, then flow, then food. Give them seasoned rock, keep the water pristine, and they will reward you with constant, charming activity. If you experiment with breeding, those rock piles and larger gravel pockets are your first smart step. Record every detail you observe so other hobbyists can build on your success.