Borneo sucker (Segama River gastromyzon)

Where they come from

Gastromyzon spectabilis is one of those classic Borneo hillstream suckers from fast, shallow jungle streams. Think clear water ripping over rounded rocks, tons of oxygen, and a constant buffet of algae and biofilm growing on every hard surface.

That background explains basically everything about them in a tank: they want current, they want clean water, and they want lots of stuff to graze.

Setting up their tank

If you treat this fish like a regular community bottom-dweller, it usually goes downhill. They are built for flow. The goal is a river-ish setup where the whole tank has moving water, not just a dead zone with a filter outlet on one side.

• Tank size: 20 gallons long is a good starting point, bigger is easier because flow and oxygen stay steadier
• Flow: strong, with a powerhead or river manifold-style circulation plus a filter that can keep up
• Oxygen: high - surface agitation matters a lot more than people expect
• Temp: cool to mid range (roughly 68-75F). They get touchy long-term in warm, sleepy water
• Substrate: smooth sand or fine gravel with lots of rounded stones and flat rocks
• Hardscape: piles of river rocks, slate shelves, and a few crevices so they can get out of each other's way
• Plants: totally optional, but tough stuff like Anubias, Bolbitis, or Java fern tied to rock works well in flow

What to feed them

They are constant grazers. You will see them rasping rocks all day, and a lot of their calories should come from that. But in most aquariums there is not enough natural growth to keep a group in good shape, so you need to add food that makes sense for a biofilm eater.

• Staples: algae wafers, spirulina pellets, and good veggie-based bottom foods
• Fresh foods: blanched zucchini, cucumber, green beans, spinach (small amounts, remove leftovers)
• Protein in moderation: frozen daphnia, cyclops, baby brine, or a little bloodworm as a treat
• Special trick: Repashy-style gel foods stuck to a rock works great because it mimics grazing

Watch their bellies. A healthy Segama River gastromyzon looks rounded, not pinched. If they are getting that hollow look behind the head or the body starts looking angular from above, they are not getting enough food (or they are getting outcompeted).

How they behave and who they get along with

They are peaceful but not pushovers. Most of the drama is sucker-to-sucker: little shoving matches over a favorite rock, quick bursts of chasing, and a lot of posturing. In a cramped tank it can turn into nonstop harassment, so give them line-of-sight breaks and more than one prime grazing spot.

• Best tankmates: small, current-loving fish like danios, white clouds (cooler temps), some rasboras, and stream loaches that are not overly aggressive
• Good clean-up buddies: nerite snails usually do fine; shrimp can work in a mature tank if nobody is stressing
• Avoid: big boisterous barbs, most cichlids, fin-nippers, and anything that wants warm, still water
• Also avoid: slow fancy fish that hate flow (they will be miserable in the same setup)

Breeding tips

Breeding Gastromyzon in home tanks happens, but it is not something I would count on. If you do everything they like - mature biofilm, cool clean water, heavy oxygen, and a calm group - you might get surprise juveniles.

• Run them in a stable group with lots of rockwork and fine gravel/sand where eggs can disappear
• Keep water very clean with frequent water changes (smaller and more often beats big sporadic changes)
• Offer plenty of grazing plus a bit of protein so adults are in good condition
• If you spot tiny copies on the glass or rocks, do not deep-clean everything at once - they need that film

Common problems to watch for

Most issues with this species come from the tank being too warm, too stagnant, too new, or too competitive at feeding time. They can look fine for a while and then slowly waste away if they are not getting enough grazing and oxygen.

• Wasting/weight loss: usually not enough food on surfaces, or faster fish stealing prepared foods
• Low oxygen stress: hanging in high-flow spots, rapid gill movement, acting lethargic in warm weather
• Bacterial/fungal patches after scrapes: often from rough rock or constant chasing in tight quarters
• Ich and other parasites: can hit hard if they arrive stressed - quarantine helps a lot
• Sensitivity to meds: many hillstream fish do not love strong dosing, especially in low-oxygen setups

One last practical thing: keep an eye on the rocks. If everything is spotless because snails, otos, or heavy cleaning are stripping it bare, these guys lose their day-to-day food source. A little green is your friend with Gastromyzon.