International Journal of Aquaculture, 2025, Vol.15, No.6, 298-307 http://www.aquapublisher.com/index.php/ija 303 and hatch on their own in the natural environment. The whole spawning behavior is usually carried out in the early morning or evening when the light is softer. It does not last long but is quite intense. Under natural conditions, yellow catfish can lay tens of thousands of eggs at one time, and the fry can hatch after about a week of embryonic development. Figure 1 Stem cell (A) transplantation (intraperitoneally) (B) of donor derived stem cells into triploid white catfish (Ameiurus catus). Transplanted stem cells migrate to the genital ridge of the recipient, are incorporated, and initiate oogenesis or spermatogenesis. Gonadal growth of the xenogeny (C). The non-injected control treatment (D) showed no fluorescence, while those injected with channel catfish (Ictalurus punctatus) stem cells were fluorescing in fry sampled at 45 (E) and 90 DPH (F) (Adopted from Hettiarachchi et al., 2024) 6.2 Effects of temperature and light on reproductive efficiency Temperature and light are key environmental factors affecting the reproductive efficiency of yellow catfish. Temperature directly determines the breeding time and embryonic development speed of yellow catfish: usually the water temperature must reach above about 18 ℃~20 ℃ before the fish gonads can fully mature and spawning activity can start. Within the appropriate temperature range (about 18 ℃~25°C), the hatching rate of fertilized eggs and the survival rate of larvae are higher; too low a temperature will delay or inhibit reproduction, while too high a water temperature may lead to abnormal embryo development or a decrease in survival rate (Chen et al., 2022). In addition, the length of light (photoperiod) affects the breeding season of yellow catfish by regulating hormone secretion in the body. As the daylight hours lengthen in spring, the gonad development of broodstock fish accelerates, and reproduction tends to be active. If the lighting time is artificially extended, the breeding period of yellow catfish can be advanced or extended to a certain extent and the frequency of spawning can be increased. However, excessive light intensity may cause stress to the broodstock, so the breeding environment should be kept with soft light (Farmer et al., 2015). 6.3 Synergistic effects of water quality and nutritional factors The quality of water and nutritional conditions will synergistically affect the reproductive success rate of yellow catfish. Excellent water quality provides a healthy environment for broodstock and embryos: high dissolved oxygen, suitable pH, low ammonia nitrogen, etc. help reduce broodstock stress, improve sperm and egg quality, and reduce embryonic mortality (Guo et al., 2021). If the water quality deteriorates (such as increased ammonia nitrogen or insufficient dissolved oxygen), even if the nutrition is sufficient, the broodstock may suffer from reduced fecundity and reduced survival rate of fertilized eggs due to stress. Likewise, adequate and balanced nutrition is crucial to gonadal development and reproductive performance of yellow catfish. Feed rich in protein, essential fatty acids and vitamins can promote female fish to produce high-quality eggs and improve fertilization
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