Borneo Sucker

Common Name

Borneo Sucker, Bornean Hillstream Loach

Origin and Habitat

Gastromyzon borneensis is native to the island of Borneo, recorded from Malaysian Borneo and Kalimantan. It lives in clear, cool forest streams that tumble over rounded stones and boulders. The fish cling to rock faces and graze in shallow riffles and runs where the current is strong and the water is highly oxygenated. Substrates are a mix of larger gravel, cobble, and bedrock with patches of sand in slower pockets. The streambed carries a living carpet of algae, diatoms, and biofilm, which is exactly what this species is built to eat.

Temperature and Water Conditions

Preferred temperature is 20 to 24°C, which is 68 to 75°F. They can tolerate the mid to upper seventies for short periods only when oxygen is very high, but long periods above 75°F increase stress. In the wild and in closely related Gastromyzon, temperatures around the low seventies are common. Keep pH near neutral with low to moderate hardness. Stable conditions matter more than chasing a precise number unless you are following a specific breeding plan. Prioritize high oxygen, strong circulation, and very clean, mature filtration.

Appearance and Size

This is a streamlined grazer with a flattened body, enlarged fins that form a suction disc, and a charming face with tiny feelers at the mouth. Color varies by locality, usually olive to chocolate with lighter speckling or bands that break across the body and fins. The dorsal and tail often show clean spots or bars that glow under good light. Sexual differences are subtle. Males can appear a touch slimmer with slightly more intense patterning, females a little rounder when full of eggs. Maximum length is about 6 cm, roughly 2.4 inches.

Diet in the Wild

A specialist aufwuchs grazer. It spends its day scraping diatoms, green algae, soft biofilm, and the tiny invertebrates that live in that film. This constant grazing supports steady energy in fast water.

Feeding in Captivity

Give them a steady buffet that mimics a living stream bed. Offer algae wafers, quality spirulina or herbivore pellets, and gel foods made for grazers. Add blanched spinach, zucchini coins, and green beans for variety. Frozen fare such as daphnia, cyclops, and baby brine shrimp make a nice supplement, not the main course. The best trick is to seed a pile of smooth river rocks in a bright tub so they grow real biofilm, then rotate those rocks into the tank for natural grazing. Feed small amounts two or three times daily so food does not foul in high flow.

Behavior and Tank Setup

Peaceful and social, this fish shines in a group of six or more. It spends most of its time attached to rock surfaces, moving in short bursts to cruise the next patch of algae. Build a hillstream style tank with a long footprint, strong directional current, and abundant oxygen. A river manifold or multiple powerheads aimed along the length work well. Use larger gravel, rounded stones, and a few flattish slate pieces for perches. Keep the glass lid tight because these fish can climb glass in strong current. Plants are optional. Hardy species like Anubias and river mosses on stones look great and will not mind the flow. Tank mates should be cool water, fast water types that ignore algae grazers. Think Sewellia, other Gastromyzon species, small Garra, danios, white cloud mountain minnows, and similar peaceful companions.

Breeding

Conditioning: Maintain cool, clean water with strong current and high oxygen. Condition a group with abundant natural grazing on biofilm rocks and regular small feedings. Rotate algae covered stones from a bright grow tub so fish have constant natural forage.

Spawning method: Spawning is subtle and usually occurs after heavy feeding and fresh water changes. Eggs are scattered among stones. There is no guarding. Build rock piles over a base of larger gravel so eggs can roll down into gaps out of reach. Strong directional flow helps eggs settle into the gravel matrix.

Raising fry: Fry are tiny, benthic, and secretive for the first weeks. The lattice of larger gravel and rock piles is essential because it traps biofilm and microfauna that fry scrape from day one. Do not vacuum the fry zone. Rotate in algae covered pebbles every few days. You can paint small stones with a thin slurry of crushed spirulina flakes and tank water, let it dry, then place them where fry hide. After a week or two, begin offering very fine powdered foods and tiny portions of newly hatched baby brine shrimp downstream of the rock piles so the current delivers food through the gaps. Perform small, frequent water changes to keep nutrients low while maintaining high oxygen. Growth is steady, and you will see miniature grazers begin to venture onto open stones after about a month.

Quick Facts

• Scientific name: Gastromyzon borneensis
• Common names: Borneo Sucker, Bornean Hillstream Loach
• Origin: Borneo forest streams with fast, clear, highly oxygenated water
• Size: About 6 cm, which is 2.4 inches
• Temperature: 20 to 24°C, which is 68 to 75°F
• pH: Near neutral, low to moderate hardness
• Temperament: Peaceful grazer, best in a group
• Diet: Biofilm, diatoms, soft algae, with spirulina based prepared foods and small frozen items
• Breeding: Egg scatterer among stones and larger gravel, fry develop in rock piles and feed on biofilm

Tropical Fish Co. Notes

Watching Gastromyzon borneensis work a rock face is surprisingly relaxing. They are little vacuum cleaners with fins, and a happy group will cruise your current like a squad of tiny flying saucers. The recipe is simple. Cool, clean, fast water. Lots of smooth stones. Real biofilm to graze. If you want to try breeding, build those rock piles and use a coarser gravel under them so eggs and fry have safe start zones. Seed extra stones in a bright tub so you can keep the buffet rolling. Keep parameters steady rather than chasing a number, and let the fish show you when they are content.