Yangtze River Whitebait

Yangtze River Whitebait

　　Anciently known as "kuican yu" (sliced leftover fish). This fish is slender in shape, transparent in body, smooth-skinned, and about the length of a finger. It prefers to inhabit the estuary of the Yangtze River near the sea. Its formal name is *Hemisalanx prognathus*, but it is commonly called "mianzhang yu" (noodle stick fish) by locals. Because this fish has fine bones, no scales, a bright silvery color, and an extremely delicious taste, it is highly favored by diners.

　　It usually lives in the main and tributary streams of the Yangtze River. It feeds mainly on plankton. Sexual maturity is reached in half a year. One-year-old fish enter lakes from rivers from April to May, breeding in areas with lush aquatic plants along the lake shores. After spawning, parent fish become noticeably thinner and soon die. It is distributed in the middle and lower reaches of the Yangtze River and its associated lakes. The individual size is not large, with the largest individuals reaching about 140 millimeters in length and weighing around 5 grams. It is an annual fish. During the breeding season, fish swarms form, and the numbers are extremely large. The whitebait is delicious, nutritious, and has a unique flavor, especially the whitebait before spawning, which is the most flavorful. In addition to being eaten fresh, most are dried and exported, with the commercial name "yan gan." Dried whitebait contains 72.1% protein and 13% fat, higher than other edible fish. Each 100 grams of whitebait also contains 4820 mg of lysine, 2308 mg of methionine, 4176 mg of isoleucine, 4396 mg of valine, and 6652 mg of threonine—such a rich array of amino acids is rare in other fish species. Each 100 grams of whitebait can provide 407 kcal of energy, nearly 5–6 times that of ordinary edible fish; it also contains 761 mg of calcium, the highest among all fish.

　　　The Yangtze River intermedia whitebait is the largest species in the whitebait family, typically measuring around 120 mm, with the largest individuals reaching up to 210 mm. It has a slender, colorless, transparent body without scales, slightly cylindrical at the front and laterally compressed at the rear. The snout is pointed and slender, the head is flat, the lower jaw is longer than the upper jaw, and there is a small adipose fin behind the dorsal fin. When viewed from above, the eyes have golden-yellow rims, and from the side, they appear silvery-white. The live fish's belly and sides have several rows of small black spots composed of pigments. Diet: The Yangtze River intermedia whitebait is a stomach-less, predatory fish. Its digestive tract is a straight tube-like intestine directly after the esophagus. There is a significant difference in diet between juveniles and adults. In the juvenile stage, it feeds on cladocerans, copepods, and some algae among plankton. After reaching a body length of 80 mm, it gradually shifts toward carnivorous feeding, and fish over 110 mm primarily feed on small fish and shrimp, exhibiting cannibalism, which is particularly severe during the dietary transition phase. The Yangtze River intermedia whitebait can swallow prey up to 33–68% of its own total length, far exceeding the proportion of 20% of their body length consumed by species such as *Erythroculter* and *Culter*.