Suan tang yu — sour fish hotpot — is the signature dish of Guizhou cuisine, and the version made in Guiyang uses a broth fermented from rice and wild vegetables over weeks before cooking, producing an acidity that is more complex than vinegar and completely unlike anything from a bottle. The dish as served in Guiyang bears no resemblance to the watered-down versions that Chinese restaurants elsewhere sometimes call "sour fish soup."
The fish is fresh river carp or grass carp, added to the broth with wood ear mushrooms, wild greens, and the fermented tofu (dofu ru) that adds a second layer of funky sourness. The cooking happens at the table over a burner. Look for restaurants specifically advertising Guizhou-style suan tang yu rather than generic hotpot restaurants; the real version requires a broth that takes two to three weeks to ferment and cannot be rushed. Qingyan Ancient Town (see /asia/china/guizhou/qingyan) and the Guizhou-style restaurants around Zhongshan Road have reliable versions.