Product Details

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

The Bloody Mary Borneo Loach is a striking specialist hillstream loach with a flattened body, powerful clinging fins and distinctive red markings that give the trade form its name. Best listed as Gastromyzon sp. “Bloody Mary”, this Borneo sucker loach is adapted to fast, cool, oxygen-rich streams and should be kept in a mature river-style aquarium rather than a standard warm community tank. It is peaceful with suitable fish, but it needs clean water, strong oxygenation and established grazing surfaces to thrive.

Key Identification:

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

Natural Range & Habitat:

Gastromyzon loaches are native to Borneo, where they inhabit shallow, fast-flowing streams and rocky hillstream habitats. The Bloody Mary form is traded as an unidentified Gastromyzon species, so exact locality details may vary between imports.

In nature, these loaches live on smooth rocks, cobbles and hard surfaces in clean, highly oxygenated water. Aquarium care should copy this as closely as possible, with strong filtration, high surface movement, bright lighting for biofilm growth and plenty of rounded stones for grazing.

Appearance & Adult Size:

Bloody Mary Borneo Loaches have the classic flattened hillstream body shape, with broad pectoral and pelvic fins that allow them to cling tightly to rocks, glass and décor. Their base colour may be brown, olive, grey, tan or patterned, with red to blood-red markings around the dorsal-fin base and upper caudal peduncle.

Adults are generally expected to remain small to medium for a Gastromyzon, often around 5–7 cm, although exact adult size may vary because the trade name is not tied to a formally confirmed species.

Aquarium Suitability:

This species is best suited to mature river-style aquariums, hillstream displays and cooler, high-oxygen community setups. It needs established algae, biofilm, smooth rocks, moderate to strong flow and very clean water.

Bloody Mary Borneo Loaches are not suitable for newly set-up aquariums, overheated tropical tanks, low-flow setups, dirty substrates, low-oxygen aquariums or tanks where all grazing surfaces are kept sterile. They should not be sold as a simple algae-cleaner for standard community aquariums.

Recommended Aquarium Size:

A practical minimum is 75–90 litres for a small group, with a tank length of at least 60–75 cm recommended. Larger aquariums are preferred because they provide more grazing area, stronger stable flow and more territories.

Footprint and surface area matter more than height. A long aquarium with smooth stones, open flow zones and multiple feeding surfaces is better than a tall bare tank.

Water Conditions:

Temperature: 20–24°C
pH: 6.0–7.5
Hardness: Soft to moderately hard
Additional Notes: High oxygen and clean water are essential. Maintain strong surface movement, good filtration and regular partial water changes. Avoid prolonged high temperatures, low oxygen, high nitrate and sudden water-chemistry swings. This species is best treated as a cool-to-moderate tropical hillstream loach.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Bloody Mary Borneo Loaches are peaceful towards suitable tank mates, although individuals may defend favourite grazing stones from other hillstream loaches. This usually appears as chasing, shuffling or display behaviour rather than serious aggression when enough space and feeding surfaces are provided.

Suitable tank mates include White Cloud Mountain Minnows, small danios, peaceful rasboras, hillstream-suitable gobies, small peaceful barbs, Otocinclus, small bristlenose plecs and other calm fish that enjoy clean, oxygen-rich water.

Avoid large predators, aggressive cichlids, goldfish, very warm-water species, delicate slow fish in excessive current, and boisterous bottom feeders that will outcompete them. Keep in a group of 3 or more, with 5 or more preferred in larger hillstream aquariums.

Feeding:

Bloody Mary Borneo Loaches graze on biofilm, soft algae, aufwuchs and tiny organisms from rock and glass surfaces. They should not be expected to survive on aquarium algae alone. Offer sinking algae wafers, spirulina foods, specialist grazer pellets, soft gel foods, blanched courgette, spinach or other shrimp-safe vegetables, and occasional small frozen foods such as daphnia, cyclops, brineshrimp or bloodworm.

Feed in several places across the rockwork if keeping a group. In community aquariums, place food directly onto grazing stones or feed after lights dim so faster fish do not take everything first.

Behaviour in the Aquarium:

This species spends much of its time attached to rocks, glass, wood and décor, grazing in short movements across surfaces. In good conditions, Bloody Mary Borneo Loaches are active during the day and may display to one another over preferred feeding areas.

They are excellent climbers and can move up glass, filter outlets and hardscape. A secure lid and covered gaps are recommended, especially in aquariums with strong flow.

Care Notes:

Add Bloody Mary Borneo Loaches only to a fully cycled, established aquarium with visible biofilm or soft algae growth. Maintain strong flow, high oxygen and very clean water. Bright lighting over smooth stones can help grow natural grazing surfaces.

Avoid copper-based medications unless confirmed safe for loaches, and never expose them to poor water quality or low oxygen. Because this is an unidentified trade form, size, colour and pattern may vary between imports. It is best sold to customers who understand hillstream aquarium care rather than as a general-purpose algae eater.

Recommended For:

Intermediate

Availability:

Occasional / 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, body colour, red markings, pattern intensity, fin shape and markings can occur between individual fish.