Gold-black Borneo sucker

Where they come from

Gold-black Borneo suckers (Gastromyzon auronigrus) come from fast, cool streams in Borneo. Think shallow riffles running over smooth rocks, tons of oxygen, and a steady buffet of algae and tiny critters living in the biofilm.

That wild setup is basically the whole secret with these fish. If you try to keep them like a normal community fish in a calm, warm tank, they usually fade out even if the numbers on the test kit look fine.

Setting up their tank

Build the tank around flow and surfaces. I have had the best results treating them like little river animals, not bottom dwellers that hang around plants.

• Tank size: I would start at 20 gallons long for a small group. More footprint beats more height every time.
• Flow: strong, messy flow across the bottom. A big canister filter plus a powerhead aimed along the front glass works well.
• Oxygen: run the tank like you mean it. Surface agitation, spray bar breaking the surface, or an airstone at night if your room runs warm.
• Substrate and hardscape: rounded river stones, cobbles, and flat rocks they can graze. Add a couple chunks of driftwood for extra biofilm.
• Plants: optional. If you use them, pick tough stuff that tolerates current (Anubias, Java fern, Bolbitis) tied to rock or wood.

Water-wise, aim for cool to mid temps and stable, clean conditions. Mine did best around 72-76F with zero ammonia/nitrite and low nitrate. They can handle a range of pH and hardness, but they do not forgive dirty water or low oxygen.

• Temperature: 70-76F is a sweet spot for most setups
• Nitrate: keep it low with regular water changes (these fish show stress fast when the tank gets "stale")
• Maintenance: vacuum detritus from calmer pockets, but do not scrub every rock spotless

What to feed them

They are grazers first. In my tanks they spend all day rasping at biofilm, algae, and whatever tiny life is growing on the stones. Your job is to keep that buffet going and back it up with real food.

• Daily staple: algae wafers or high-quality spirulina-based tablets (I like to break them into smaller pieces so everyone gets some)
• Greens: blanched zucchini, cucumber, green beans, or spinach (clip it down so the current does not launch it)
• Frozen: baby brine shrimp, daphnia, cyclops, or finely chopped bloodworms as a protein boost a few times a week
• Gel foods: great for hillstream types because you can smear it onto a rock and they will graze naturally

Watch bellies. A well-fed Gastromyzon has a gently rounded belly, not pinched in. If you see hollow bellies or they start parking in one spot all day, rethink food and flow before you blame disease.

How they behave and who they get along with

They are busy little suction-cup pancakes. Most of the time they are peaceful, but they do have opinions about favorite rocks. You will see little shuffles, short chases, and "body blocking" more than real fighting.

• Group size: keep several if you can (3-6+). They act more natural and spread out the squabbles.
• Good tankmates: small, current-loving fish like danios, white clouds, some rasboras, and other gentle hillstream species.
• Avoid: big bottom feeders that outcompete them (large loaches, big plecos), aggressive fish, and anything that needs warm, calm water.
• Shrimp/snails: usually fine. Shrimp also help keep surfaces busy with biofilm growth.

Breeding tips

Breeding can happen in home tanks, but it is not a "put them together and you get fry" situation. The biggest hurdle is getting adults settled, well-fed, and living in a tank that feels like a river.

If you want to take a swing at it, I have seen the best odds with a mature, algae-rich setup, strong current, and lots of small crevices between stones. Some keepers report spawning after a few big cool water changes that mimic rain.

• Give them rock piles with gaps and undersides (safe spots and possible egg scatter areas)
• Keep food heavy but clean: lots of grazing surfaces plus small daily offerings
• Try seasonal cues: slightly cooler, larger water changes for a couple weeks
• If you spot tiny fry: do not deep-clean the tank. They need microfoods and biofilm

Common problems to watch for

Most issues with Gastromyzon are husbandry problems wearing a disease mask. These fish do not give you a lot of warning, so small changes in behavior matter.

• Starvation in a new or "too clean" tank: hollow bellies, weak grip, less grazing
• Low oxygen: hanging in high-flow zones only, rapid breathing, lethargy especially at night
• Heat stress: acting wiped out in summer, increased breathing, hiding more (they like it cooler than many community fish)
• Bloat/constipation: often from too much rich food without enough grazing and greens
• Rough shipping and parasites: thin body despite eating, flashing, clamped fins (quarantine helps a lot with this species)

My personal checklist if one looks off: check temperature, crank surface agitation, test ammonia/nitrite, do a decent water change, and add an extra feeding on a rock (gel or wafer) to see if it perks up. If the fish still declines, then I start thinking quarantine and targeted treatment.