Yunnan loach

Where they come from

Yunnan loaches are small stone loaches from the mountain streams of Yunnan, China. Think cool, clear water tumbling over rounded stones with lots of oxygen and little fine muck. That setting tells you almost everything about how to keep them happy.

Setting up their tank

Give them floor space and flow. A 20-gallon long (or larger) works for a group, with more footprint over height. They spend their time on the bottom, wedging under stones and darting between cracks.

• Substrate: fine sand or very smooth small gravel. Sharp grit will chew up their barbels.
• Hardscape: rounded river stones, slate stacks, driftwood branches. Build lots of crevices.
• Plants: tough, cool-tolerant epiphytes like Java fern, Anubias, Bolbitis, and mosses tied to wood/rock.
• Cover: tight lid. They can and will find gaps during lights-off dashes.

Flow and oxygen make the difference. Use a canister or big sponge filter plus a powerhead or spray bar to push water along the length of the tank. If you like DIY, a river-manifold setup keeps a steady one-direction current. Add extra surface agitation or an airstone for hot days.

Targets that have worked for me: 18-22 C (64-72 F), pH 6.5-7.6, GH 3-12 dGH. They can handle cooler nights, but avoid letting them sit at 24 C+ for weeks. Weekly 30-50% water changes keep the substrate clean and the oxygen up. Keep lighting moderate and give shady spots; they relax more and show better behavior.

What to feed them

They are bottom pickers that graze biofilm and hunt tiny critters. Mine really wake up at dusk, so I feed then. Sinking foods are the way to go, and a bit of variety keeps them in good shape.

• Staples: high-quality sinking wafers, small pellets, or Repashy gel (Soilent Green, Community Plus).
• Meaty treats: frozen cyclops, daphnia, baby brine shrimp, bloodworms (sparingly), blackworms.
• Extras: blanched zucchini rounds, spinach, and occasional crushed snails or snail eggs.
• Biofilm boost: let wood and rocks grow a little algae and periphyton. They will graze it.

How they behave and who they get along with

They are busy but not bullies. In a group of 6+ they settle faster, spread out the occasional squabble, and you see more natural foraging. Expect quick dashes and some chasing, then everyone goes back to sifting sand or perching under a rock lip.

• Good company: White Cloud Mountain minnows, cooler-water danios and rasboras, smaller Garra species, hillstream loaches, ricefish, Amano shrimp.
• Use caution: dwarf shrimp may lose babies to nighttime snacking.
• Skip: big cichlids, loach-eaters, fin-nippers like tiger barbs, and anything that needs warm, still water (bettas, fancy guppies).

Breeding tips

Documented home spawns are rare, but stone loaches often scatter eggs in crevices if the mood strikes. I have not had a confirmed raise to adulthood, but I have seen post-spawn behavior and a couple of free-swimmers appear in a mature, rock-heavy setup.

• Set up a cool-flow tank with piles of smooth stones, marbles, or mesh so eggs can fall out of reach.
• Condition with heavy feeding on live and frozen foods for a few weeks.
• Try a series of cool water changes, then slightly warmer (2-3 C swing) to mimic rains.
• Run a sponge filter only in the breeding tank to protect tiny fry from intakes.
• If eggs hatch, start with green water, infusoria, or paramecium, then move to microworms and baby brine.

Common problems to watch for

Most issues come down to heat, low oxygen, and dirty substrate. Keep up the flow and housekeeping and they are sturdy little fish.

• Heat waves: watch for gulping at the surface. Add fans, float ice bottles, and crank up surface agitation.
• Barbel erosion: usually from sharp gravel or gunked-up sand. Swap to fine sand and vacuum lightly every water change.
• Skinny loach syndrome: internal parasites show as eating well but losing weight. Quarantine new fish and treat with a dewormer like levamisole or flubendazole as needed.
• Ich and other external parasites: they can be sensitive to meds. Use half-doses to start, boost oxygen, and avoid copper unless you know the concentration.
• Jumping and filter accidents: tight lid, covered intakes, and blackout tape on lid gaps save lives.
• Stress from bright light: add more cover or floaters. Stressed fish hide and skip meals.