Marsh Yunnan loach

Where they come from

Marsh Yunnan loaches are little bottom-huggers from Yunnan, China. Think quiet marshes and backwaters with soft sand, leaf litter, and clumps of grasses. The water is usually cool to mild, not roaring like a hillstream, and the bottom is where all the action is.

Setting up their tank

Give them floor space over height. A 20-gallon long (or any 24-30 inch footprint) works well for a small group. They spend their time on the substrate, sifting and darting under cover.

• Substrate: fine sand, sugar-grain size. They like to nose into it.
• Cover: driftwood roots, smooth stones, leaf litter, and clumps of hardy plants or grasses.
• Flow: gentle to moderate. You want clean, well-oxygenated water without blasting them around.
• Filtration: a sponge or canister with a prefilter on the intake so nobody gets stuck.
• Lid: tight-fitting. They can and will find gaps.

Keep the water on the cooler side of tropical. They handle room-temperature tanks well as long as it is stable and clean.

• Temperature: 18-24 C (64-75 F)
• pH: roughly 6.2-7.4
• Hardness: soft to mid (2-10 dGH)
• Maintenance: small weekly changes and regular substrate siphoning around, not into, their hidey-holes

What to feed them

They are micro-predators and pick at tiny critters. Mine woke up for anything that wiggled and eventually learned pellets, but it took patience.

• Live or frozen: baby brine shrimp, daphnia, cyclops, bloodworms (chopped if large), blackworms
• Dry: quality sinking micro-pellets, crushed wafers, bug-based granules
• Occasional veggie nibble: crushed spirulina wafer for variety

How they behave and who they get along with

Shy at first, then busy little sand-sifters once they feel safe. They like a group; I would do 6+ so they are not skittish. Expect more evening activity.

• Good tankmates: white cloud mountain minnows, small danios, ricefish, peaceful rasboras, small pencilfish, pygmy Corydoras (if temps overlap), shrimp (adults), and snails.
• Avoid: big or boisterous fish, nippy barbs, anything that hogs the bottom, and strong river setups meant for hillstream species.
• They will snack on very tiny shrimp or shrimplets. If you want a shrimp colony, add plenty of moss and hides.

Breeding tips

These are classic scatterers. I have not had a full raise-up in a display, but I have seen eggs show up in leaf piles after a cool water change.

• Set up a separate 10-15 gallon with fine sand, lots of leaf litter, and fine plants or yarn mops.
• Condition adults with live and frozen foods for 2-3 weeks.
• Do a slightly cooler water change (2-3 C drop) in the evening and dim the lights.
• Adults will scatter eggs among leaves and sand. Pull parents after a day or use marbles/mesh so eggs fall out of reach.
• Eggs hatch in 2-3 days depending on temp. Start fry on infusoria or green-water, then microworms and newly hatched brine shrimp.
• Gentle sponge filtration only. Keep it clean and calm.

Common problems to watch for

• Barbel damage from rough substrate or dirty sand. Switch to fine sand and improve cleaning rhythm.
• Starving in community tanks because they are shy feeders. Target-feed and add more cover.
• Import stress: ich and flukes show up often. Quarantine new fish for 3-4 weeks.
• Medication sensitivity: many loaches react badly to copper, formalin, and full-dose dyes.
• Overheating in summer. Above mid-70s F for long stretches can stress them. Use fans or float ice bottles if needed.
• Getting stuck: they will explore. Use a prefilter sponge on intakes and close cable gaps in the lid.