Product Details

Bloody Mary Borneo Loach – Gastromyzon sp. “Bloody Mary”

Overview:

The Bloody Mary Borneo Loach is a specialist hillstream loach with a flattened body, powerful clinging fins and distinctive red markings that make it one of the most eye-catching Gastromyzon imports. This unusual Borneo sucker loach is not a general algae eater for a warm community aquarium; it is a rheophilic species that needs cool, clean, oxygen-rich water and a mature aquarium with strong flow. In the right river-style setup, it is a fascinating grazer that spends much of its time attached to smooth stones, glass and décor.

Key Identification:

Common Name: Bloody Mary Borneo Loach
Other Names: Bloody Mary Hillstream Loach, Red Lamandau Hillstream Loach, Double Red Borneo Loach, Borneo Sucker, Red Borneo Sucker
Scientific Name: Gastromyzon sp. “Bloody Mary”
Fish Type: Hillstream Loach / Borneo Sucker
Water Type: Freshwater

Natural Range & Habitat:

The Bloody Mary Borneo Loach is a Borneo hillstream species currently traded under a provisional name. Trade references link it with fast-flowing, well-oxygenated streams of Borneo, and the name Red Lamandau suggests a Lamandau-area locality or trade association. Aqua Imports describes it as a smaller-growing hillstream loach from fast-moving, well-oxygenated Bornean streams, while Seriously Fish notes that Gastromyzon species are specialised inhabitants of swift, shallow, oxygen-saturated streams.

In nature, these fish live among rocks, pebbles and submerged surfaces coated with algae, biofilm and aufwuchs. Aquarium care should focus on replicating this clean, fast-water environment rather than treating them as ordinary tropical bottom fish.

Appearance & Adult Size:

This loach has the flattened, streamlined shape typical of Gastromyzon, with broad paired fins that act like suction pads in strong current. The body is usually dark brown to blackish with lighter spotting or mottling, while the “Bloody Mary” feature is the red to blood-red marking around the dorsal base and upper tail section. Aquarium Glaser specifically describes the red markings at the base of the dorsal fin and on the upper side of the caudal peduncle.

Adults are relatively small, usually around 5–6.5 cm, making them compact but still specialist fish. Their small size does not mean they are suitable for small, low-flow tanks.

Aquarium Suitability:

This species is best for a dedicated hillstream, river-style or high-oxygen subtropical aquarium. Provide smooth rounded stones, cobbles, wood, open grazing surfaces and strong water movement. Bright lighting can be useful for encouraging algae and biofilm growth, provided shaded retreats are also available. A mature tank is strongly recommended because these loaches rely heavily on established grazing surfaces.

They are not suitable for standard warm community aquariums, low-oxygen setups, soft muddy substrates or tanks without flow. Practical Fishkeeping notes that hillstream and brook loaches require cooler water, very high flow and high oxygenation rather than normal community conditions.

Recommended Aquarium Size:

A practical minimum is 75–90 litres for a small group, with 120 litres or more preferred for better flow, oxygen stability and grazing space. A longer aquarium is more useful than a tall one, as these fish live on surfaces and benefit from a broad footprint.

Water Conditions:

Temperature: 20–24°C
pH: 6.5–7.5
Hardness: Soft to moderately hard; avoid unstable extremes
Additional Notes: High oxygen levels, strong filtration and moderate to fast flow are essential. Seriously Fish recommends 20–24°C for general care of similar undescribed Gastromyzon forms, while Aqua Imports notes that Bloody Mary Hillstream Loaches prefer slightly cooler water with clean, well-aerated conditions and moderate to fast flow. Avoid consistently high tropical temperatures, stagnant areas and poor water quality.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Bloody Mary Borneo Loaches are peaceful, but they are specialised fish and should be kept with species that enjoy similar cool, oxygen-rich water. Suitable tank mates include White Cloud Mountain Minnows, small danios, hillstream loaches, Rhinogobius-type gobies, small peaceful barbs and other active stream fish that will not outcompete them too aggressively.

Avoid large predators, aggressive cichlids, warm-water community fish, slow delicate species and boisterous bottom-feeders that may block grazing areas. They are best kept in a group of at least 5, where space allows. Aqua Imports also recommends groups of at least five for this social loach.

Feeding:

This species is a specialised grazer and opportunistic feeder. It should have access to mature algae, biofilm and aufwuchs on stones, wood and glass. Supplement with algae wafers, spirulina foods, Repashy-style gel foods, fine sinking pellets, blanched vegetables and occasional frozen foods such as daphnia, cyclops, brineshrimp or bloodworm. Aqua Imports recommends a varied diet high in algae or vegetable content, while Aquatic Arts lists algae, sinking pellets and blanched vegetables as suitable foods.

Do not add to a sterile new aquarium with no grazing surfaces, as newly imported hillstream loaches may be reluctant to take prepared foods at first.

Behaviour in the Aquarium:

Bloody Mary Borneo Loaches spend much of their time attached to rocks, glass, filter outlets or wood, grazing and repositioning themselves in the current. They may spar gently over favoured stones, but this is usually display behaviour rather than serious aggression. Their body shape allows them to cling tightly in strong flow, and they often choose the most oxygen-rich parts of the aquarium.

Care Notes:

This is a specialist loach for mature, high-oxygen aquariums. Strong flow, clean water and stable cooler temperatures are essential. Use smooth stones and avoid sharp décor that could damage the underside. Encourage natural biofilm growth before purchase, and make sure prepared foods reach the fish rather than being swept away or stolen by faster tank mates. Do not keep in hot, low-flow tropical tanks. A secure lid is recommended, as loaches can climb glass and explore filter outlets.

Recommended For:

Intermediate to experienced

Availability:

Rare / Seasonal / Specialist import

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 and markings can occur between individual fish.