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Golden Stork and Rainbow Gills Photoperiodic Mature Four Seasons Breeding Technology
Shen Xishun and Wang Zhaoming from the Beijing Shunhong Rainbow Trout Culture Center (Huairou, 101400) guide visitors through their state-of-the-art aquaculture facility. The incubation room features a white juvenile pond where golden pheasants and rainbow trout swim and feed. The fish farmer carefully distributes bait, while General Manager Shen Xishun explains the breeding process to the guests.
Golden pheasants and rainbow trout are cold-water species that naturally spawn between November and February each year. However, this limited breeding window often creates shortages in seedling supply for farmers throughout the year. To address this challenge, the center has developed advanced techniques based on foreign technology and the biological traits of these fish, enabling year-round breeding of both species. This innovation supports the growth of the aquaculture industry by ensuring a consistent supply of high-quality seedlings.
Outside, the broodstock ponds are filled with golden pheasants and rainbow trout. Their reproductive cells, known as primordial germ cells, grow in size as daylight hours decrease and water temperatures drop. By winter, these cells develop into eggs measuring 4 to 6 mm, ready for fertilization. This natural cycle led researchers to discover that light exposure significantly influences germ cell development. Through years of experimentation, they successfully created an optically controlled maturation technique, allowing breeders to manipulate the spawning season. Now, golden pheasants and rainbow trout can be bred not just in winter but also in summer and autumn, meeting market demands all year round.
In one area, large white stainless steel troughs are set up on metal frames. Each trough houses about 20 goldfish and four brooders. A black shading curtain is used to control sunlight exposure. In early March, when daylight lasts around 10 hours, the curtain is deployed in the afternoon to reduce illumination to 6–8 hours, triggering an early short-day period. This accelerates gonadal development, enabling fish that would normally mature in November to reach maturity as early as September.
Another section features wooden sides with 40-watt fluorescent lights installed underneath. At night, the lights are turned on to simulate longer days. By extending light exposure from 11 to 17 hours, the fish’s reproductive cycle is delayed. Once artificial lighting stops in March and daylight shortens again, the fish begin to mature once more, with their breeding season shifting to June or July. This allows for the production of summer seedlings.
Outdoors, aquarists carefully select broodstock for artificial egg collection. Fish that have been exposed to controlled lighting enter the maturation phase and are then manually bred. Selected fish are placed in small cages, where eggs and sperm are collected. Under a large parasol, one worker uses a net to collect eggs, while another gently squeezes the fish's abdomen to extract the oocytes. The eggs are rinsed with isotonic solution before being transferred to an insemination pot.
A second worker adds male fish semen to the pot, and the mixture is stirred by hand before being poured into clean water. Fertilized eggs are then placed in hatching tanks, where they remain undisturbed for one hour to avoid vibration, which could damage them. Afterward, they are moved to flowing water for incubation.
In another part of the facility, rainbow trout fry are raised in white and blue basins. At a water temperature of 10°C, the eggs hatch after 32 days, and fry begin feeding after 30 days. These young fish are then sold as seedlings to farms and households, supporting local aquaculture efforts.
Through the use of light-controlled breeding techniques, the Shun Tong Rainbow Trout Culture Center ensures that golden pheasants and rainbow trout can be bred in all seasons. This enables farmers to obtain seedlings according to seasonal needs and supply commercial fish to the market year-round, promoting sustainable aquaculture practices.