Huangwei gu (黄尾鲴)

Where they come from

Yellowtail sharpbelly (Xenocypris davidi) are Chinese river fish. Think big, moving water - broad rivers, reservoirs, and open stretches where they can cruise and pick at food all day. They are built like little torpedoes, and they act like it in the aquarium too.

Setting up their tank

Plan for a long tank and a lot of swimming room. They are active, fast, and nervous in cramped setups. A 6 foot tank is where they start looking relaxed, and bigger is honestly better if you want a group.

• Tank size: 125+ gallons for a small group, 180+ is much easier to manage
• Footprint matters more than height - go long and wide
• Keep the middle open; put hardscape along the edges so they have lanes to sprint

They do best with strong filtration and noticeable flow. I like running a canister plus a big powerhead (or two) aimed along the back glass to make a circular current. If you can get them surfing the current without being pinned to one spot, you are in the right zone.

• Temperature: mid-to-cool side freshwater works well (around 68-75F / 20-24C)
• pH: they are pretty flexible if its stable (roughly 6.8-8.0 has worked for people)
• Oxygen: high - use surface agitation and do not baby the flow

Substrate is your choice. Sand looks nice and keeps things natural, but they are not big diggers. What they do appreciate is clean water, so set the tank up so you can vacuum easily and keep mulm from building up in dead spots.

What to feed them

They are basically river omnivores with a strong plant and plankton vibe. In a tank they eat like little pigs, but they stay in better shape if you feed like a grazer rather than a predator. Small meals, variety, and a lot of roughage.

• Staples: quality pellets or sticks for omnivores/cyprinids (not super fatty)
• Greens: blanched spinach, romaine, zucchini, peas (shelled)
• Protein treats: frozen daphnia, brine shrimp, bloodworms (sparingly), chopped earthworm
• Extras: spirulina flakes, repashy-style gel foods if you already use them

They are fast eaters and will outcompete calmer fish. Spread food across the tank, and if you keep them with slower species, use sinking foods and feed in two spots.

How they behave and who they get along with

They are schooling fish, and a small group acts way better than a singleton. Alone, they can get skittish and bashy. In a group, they settle into that constant cruising behavior and spook less.

• Group size: 6+ if you have the room and filtration
• Temperament: not predatory, but very pushy at feeding time
• Activity: high - they want open water and current

Tankmates should be sturdy, mid-to-large fish that like cooler temps and flow. Think other large cyprinids or river-type fish. Avoid slow, delicate finned fish and anything that will be stressed by constant motion.

• Good matches: larger barbs, danio relatives, other robust Chinese minnows/carp family fish, larger loaches that like flow
• Risky: angelfish, fancy goldfish, long-finned anything, slow bottom dwellers that get bulldozed at meals
• Avoid: tiny fish you care about - not because they hunt, but because chaos happens

Breeding tips

Breeding them at home is not the usual aquarium project. In the wild they spawn seasonally with temperature and flow cues, and they are typically bred in ponds or large systems. In a home tank, you might see chasing and schooling behavior ramp up, but getting viable spawns and raising fry is a long shot unless you can dedicate serious space.

Common problems to watch for

Most issues trace back to three things: not enough oxygen/flow, not enough space, or messy water from heavy feeding. They are hardy once settled, but they do not forgive a cramped, under-filtered tank.

• Spooking and crashing into glass: usually from sudden lights, tapping, or too-small quarters
• Nose/mouth abrasions: from repeated darting into decor or glass during panic runs
• Gasping or hanging near the surface: oxygen or circulation problem first, not a medicine problem
• Bloat/stringy poop: often diet related (too much rich protein, not enough fiber)
• Ich after purchase: stress plus cool-water fish in fluctuating temps can trigger it

Quarantine is worth doing with this species. They ship poorly sometimes, and a stressed, newly imported fish in a big fast-flow display tank can turn into a pinball. A calmer quarantine tank with strong aeration, dim lighting, and predictable feeding helps them settle before you move them into the main river setup.