Erythroculter ilishaeformis, also known as Whitefish or "Three Whites" of Taihu Lake, is one of the most esteemed freshwater fish in China. Often referred to as the "Whitefish of Taihu," it is considered the top species among the "Three Whites" and has long been a symbol of high-quality aquatic produce from the region. This fish thrives in open rivers and lakes, primarily feeding on small fish from the upper water layers. Due to the abundance of natural food sources in the middle and lower reaches of the Yangtze River and surrounding lakes, these fish are known for their superior flavor.
For successful breeding, a well-designed pro-fish pond is essential. The pond should have a sufficient water supply, clean and pollution-free water, and good drainage systems. An ideal size ranges from 1 to 3 mu (approximately 0.67 to 2 hectares), with a depth of about 1.5 meters. If the broodstock pond is too large, it may lead to overcrowding, which can damage the fish and affect their feeding and spawning. It's best to place the broodstock nursery near the spawning pond for easier handling and to reduce mortality during transfers.
During winter, when water temperatures hover around 10°C, adult fish weighing over 1,000 grams and at least three years old are collected from natural waters like rivers and lakes. These fish must be handled carefully to avoid dehydration. Transport methods include using oxygenated water bags, live water containers, or specialized transport tanks. If raised in ponds, they should be netted and exercised a few times before being moved. Commercial farmed fish can also be used, but inbreeding should be avoided. Before stocking, fish are briefly soaked in a 5% saltwater solution for disinfection, then placed into the pond at a density of about 200 kg per mu. Their diet mainly consists of small fresh fish, and feeding should be frequent—every 3 to 5 days. Fresh fish can be cut into small pieces and fed directly.
To identify mature broodstock, it’s important to observe physical characteristics. From June to early July, when water temperatures reach 26°C, breeding can begin. Male fish will show white pearl-like spots on their heads, pectoral fins, and back, and their abdomens will feel rough. When gently pressed, semen may be released from the reproductive opening. Males should weigh at least 0.8 kg. Female fish have smooth skin, swollen and soft bellies, and visible ovarian outlines, with a weight of over 1 kg. The male-to-female ratio should be between 1:1 and 1.5:1.
Spawning and hatching require careful setup. Spawning and hatching pools can be separate or the same. If combined, a circular structure with a diameter of 3 to 4 meters is ideal. The pool should be about 1 meter deep, with vertical water outlets at the bottom and a 60-mesh sieve at the center. Water sources must be clean and fresh. In early June, when the temperature rises to 26–28°C, hormones such as LHRH-A2, DOM, and HCG are used to induce spawning. Each pool can hold 6 to 10 groups of broodstock, with a water flow rate of approximately 0.1 m/s. A small amount of brown tablets or PVC mesh is placed to aid in egg attachment. After placing the broodstock, a mesh cover is added to prevent them from jumping out.
The hormone mixture includes 10 μg/kg LHRH-A2, 5 mg DOM, and 1000–1500 IU HCG for females, while males receive half the dose. After injection, the fish are left for 8–10 hours. Spawning can occur naturally or through artificial insemination. If natural, the broodstock are monitored, and after spawning, healthy individuals are retained. Eggs are hatched in the same pool.
For artificial insemination, when the broodstock shows signs of readiness, they are separated, dried, and eggs and sperm are mixed in a dry basin. Stirring with a feather or finger ensures proper fertilization. After a few minutes, the eggs are washed in clean water and transferred to a hatching bucket. If no hatchery is available, they can be placed in a large container. One person collects the eggs, another places them on the ovary, and the ovary is then put into the water. Hatching density should be around 500,000–800,000 fry per cubic meter. After about 30 hours, the larvae develop, and once the swim bladder forms and the eyes darken, they are transferred to fry cultivation ponds for further growth.
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