Yangi loach

Where they come from

Yunnanilus yangi is a little hillstream-style loach from Yunnan, China. Think cool, clear water with steady flow, lots of oxygen, and a bottom made of smooth stones, gravel, and leaf bits. They are not a "warm community tank" fish, and that mismatch is where most people run into trouble.

Setting up their tank

Aim for a tank that feels like a shallow stream section. You want flow, oxygen, and lots of "ground level" structure. They spend their time weaving through rocks and plants, parking themselves in calm pockets, and picking at the bottom.

• Tank size: I would start at 20 gallons long (75 cm) for a group. Smaller can work, but your margin for error gets thin fast.
• Temp: cool side of freshwater. I keep mine in the high 60s to low 70s F (around 20-23 C). Avoid hot tanks.
• Flow and oxygen: a strong filter, a powerhead, or a spray bar aimed along the length. Add an airstone if you do not see good surface movement.
• Substrate: smooth sand or fine gravel. Add rounded river stones and pebble piles. Skip sharp gravel - their bellies and fins will tell you.
• Hiding spots: rock stacks (stable), small caves, wood, and dense plants. They relax more when they can disappear.
• Lighting: moderate is fine. I like some shaded zones so they are not "on display" 24/7.

I strongly recommend a mature tank with biofilm. New setups can look clean but still feel sterile to them. A few months of stability (and a bit of green on the rocks) makes a noticeable difference in how quickly they settle and start feeding confidently.

What to feed them

They are pickers. In my tanks they spend a lot of the day grazing micro-foods off surfaces, then they get serious at feeding time. The trick is variety and getting food down to the bottom without everything being stolen by faster fish.

• Staples: sinking micro pellets, small sinking wafers, and soft gel foods if you use them.
• Frozen: cyclops, daphnia, baby brine, chopped bloodworms (sparingly), and mysis if the pieces are small enough.
• Live (best for conditioning): baby brine shrimp, grindal worms, small blackworms if you trust your source.
• Grazing support: let some rocks grow biofilm and a light dusting of algae. Do not keep the tank "too sterile."

Watch their bellies. A healthy Yunnanilus has a gently rounded belly after meals, not pinched-in. If they look hollow even though you are feeding, it is usually competition, internal parasites, or the fish never really settled.

How they behave and who they get along with

They are peaceful, a little shy at first, and much more fun in a group. You will see low-key sparring and chasing, but it is more about sorting out personal space than actual damage.

• Group size: 6+ is where they start acting natural. Smaller groups stay skittish.
• Good tankmates: other cool-water, non-bullying fish that like flow (think small danios and similar), and gentle bottom dwellers that will not outcompete them.
• Avoid: big boisterous fish, aggressive loaches, and anything that turns feeding time into a food tornado.
• Shrimp: depends. Small shrimp may become snacks, but adults often do fine if the tank has cover.

Breeding tips

Breeding is possible, but it is not a "throw them in and hope" fish. Most of my progress has come from giving them seasons: cooler period, then a gradual warm-up and heavier feeding, plus lots of fine-leaved plants and crevices where eggs can disappear.

• Conditioning: 2-3 weeks of heavier feeding (live/frozen) with big water changes.
• Trigger: a slightly cooler water change followed by stable temps and strong flow has worked better for me than chasing exact numbers.
• Spawning sites: moss, fine plants, leaf litter, and rock gaps. They like places where eggs are not easy to find.
• Egg safety: adults may snack. If you see fry or suspect eggs, moving adults or using a separate spawning tank improves your odds.

Common problems to watch for

Most issues come from the same few themes: too warm, not enough oxygen/flow, or the tank not being stable enough yet. They also do not love being shipped, so the first couple of weeks matter.

• Gasping or hanging near the surface: almost always oxygen/flow or dirty filter media. Increase surface agitation and check for clogged intakes.
• Hiding all the time and not eating: stress from bright open tanks, too much competition, or a new tank with no biofilm. Add cover and feed more targeted sinking foods.
• Rapid weight loss: often internal parasites. Quarantine new fish if you can and do not ignore stringy white poop or pinched bellies.
• Battered fins or scrapes: sharp decor, unstable rock stacks, or being kept with pushy tankmates.
• Sudden losses after a hot spell: heat plus low oxygen is a nasty combo for these. Summer temps can be the silent killer.

If you set them up like a little stream and keep up with maintenance, they are incredibly rewarding. Once settled, you will see more daylight activity, bolder feeding, and those constant little bottom-wiggles that make stone loaches so addictive.