Product Details

Blue Tail Borneo Loach – Gastromyzon sp. “SK03”

The Blue Tail Borneo Loach is a specialist hillstream loach with a flattened body, gripping fins and attractive blue-toned markings in the tail and fins. Also sold as the Blue Tail Borneo Sucker, Blue Tail Butterfly Borneo Sucker Loach, Borneo Sucker Loach or Gastromyzon SK03, this is a peaceful but demanding freshwater fish for mature aquariums with strong flow, high oxygenation and natural biofilm growth. It is best suited to a river-style setup rather than a standard warm community aquarium.

Key Identification:

Common Name: Blue Tail Borneo Loach
Other Names: Blue Tail Borneo Sucker, Blue Tail Butterfly Borneo Sucker Loach, Borneo Sucker Loach, Hillstream Loach, Gastromyzon SK03
Scientific Name: Gastromyzon sp. “SK03”
Fish Type: Hillstream Loach / Borneo Sucker Loach
Water Type: Freshwater

Natural Range & Habitat:

Gastromyzon loaches are native to Borneo and nearby parts of Southeast Asia, where they live in shallow, fast-flowing hill streams and river systems. These habitats are usually clear, cool to moderately warm, highly oxygenated and rich in smooth stones, cobbles, bedrock and natural biofilm.

The SK03 form is a trade-coded Gastromyzon rather than a fully confirmed species name, so exact locality may vary between imports. In the aquarium, it should be treated as a specialist Borneo hillstream fish that needs clean moving water, grazing surfaces and excellent stability.

Appearance & Adult Size:

Blue Tail Borneo Loaches have a broad, flattened body with enlarged pectoral and pelvic fins that help them cling tightly to rocks, glass and other hard surfaces. The body is usually brown, grey, olive or dark-toned with fine striping, spotting or reticulated markings that help it blend into a stony stream environment.

The tail and fins may show blue, dark or contrasting highlights, especially under good lighting and when the fish is settled. Adults usually reach around 4–6 cm.

Aquarium Suitability:

This species is best suited to a mature river-style aquarium with strong water movement, high oxygen levels and plenty of smooth rocks for grazing. Bright lighting can help encourage natural algae and biofilm growth, while shaded areas give the fish places to rest.

It is not suitable for sterile new aquariums, warm low-flow tropical tanks or setups with poor circulation near the substrate. Blue Tail Borneo Loaches should be seen as specialist grazing fish, not general-purpose algae cleaners.

Recommended Aquarium Size:

A practical minimum is 90 litres for a small group, with a tank length of at least 90 cm preferred. Larger aquariums are better for multiple hillstream loaches or active current-loving tank mates.

Keep in a group of at least 3–5 where space and food availability allow. Multiple smooth rocks and grazing areas help reduce competition between individuals.

Water Conditions:

Temperature: 20–24°C
pH: 6.5–7.8
Hardness: Soft to moderately hard
Additional Notes: Strong oxygenation is essential. Provide moderate to strong flow using an external filter, powerhead or river-style setup. Keep nitrate low and avoid high temperatures, stagnant areas, dirty substrate and unstable water conditions.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Blue Tail Borneo Loaches are peaceful with most fish, although they may gently chase or push each other away from favourite rocks and feeding areas. This behaviour is usually territorial display rather than serious aggression when enough space is provided.

Suitable tank mates include White Cloud Mountain Minnows, small danios, peaceful rasboras, small stream-suitable barbs, hillstream gobies and other calm fish that enjoy cool, clean, well-oxygenated water. Avoid goldfish, large predators, aggressive loaches, very warm-water species, delicate long-finned fish and slow tank mates that dislike strong current.

Feeding:

Blue Tail Borneo Loaches are specialised surface grazers. In nature, they feed mainly on biofilm, soft algae, diatoms and tiny invertebrates from rock surfaces. In the aquarium, provide mature grazing surfaces and supplement with algae wafers, spirulina foods, specialist gel foods, sinking micro pellets and fine catfish foods.

Small frozen or live foods such as daphnia, cyclops, brineshrimp and occasional bloodworm can be offered, but the diet should not be too rich in meaty foods. Blanched courgette, spinach or kale may also be accepted. Do not add this fish to a newly set-up tank with no natural biofilm.

Behaviour in the Aquarium:

This is a clinging and grazing fish rather than a typical swimming loach. It spends much of its time attached to smooth stones, glass, wood or broad leaves, moving in short gliding bursts as it grazes across surfaces.

It often chooses high-flow areas near filter outlets or powerheads and may rest flat against rocks between feeding periods. In groups, individuals may defend small grazing spots, but serious damage is uncommon in a well-designed aquarium with enough hardscape.

Care Notes:

A mature aquarium is essential. Provide strong flow, high oxygenation, smooth stones, stable water and established biofilm. Avoid high temperatures, low oxygen, sharp décor and dirty substrates.

Make sure prepared foods reach the loaches, especially in tanks with fast midwater fish. This species is not suitable for brand-new aquariums or standard warm community tanks with weak filtration. Regular water changes and low nitrate levels are important for long-term success.

Recommended For:

Intermediate to experienced

Availability:

Rare to occasional / Usually wild-caught or imported under specialist Borneo hillstream loach trade names

Image Disclaimer:

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Natural variation in size, colour, pattern, body tone and markings can occur between individual fish.