Fish rickets, based on their causative agents, can be categorized into bacterial gill disease, fungal gill disease (also known as mold or mycosis), and parasitic gill disease. These conditions significantly impact fish health and aquaculture productivity. Bacterial gill disease is one of the most common infectious diseases affecting fish. It often occurs alongside bacterial enteritis and red skin disease, posing a serious threat to grass carp and adult fish species. In severe outbreaks, grass carp mortality can reach up to 60%, and other species such as herring, salmon, and squid are also at risk. With the rise of high-density and intensive aquaculture practices, even less traditional farmed species like catfish, tilapia, and clams have been increasingly affected, with mortality rates frequently exceeding 40%. This disease has become a major challenge for the aquaculture industry, prompting extensive research and the development of effective prevention and control strategies. **I. Pathogens** 1. **Bacterial Gill Disease**: The primary pathogen responsible for this condition is *Myxococcus*. These bacteria are slender, flexible, and typically measure around 0.3 microns in diameter. They are usually straight or slightly curved, appearing in shapes such as U, V, Y, or semi-circular. Growth occurs through transverse division, and they do not possess flagella, relying instead on gliding or shaking for movement. Optimal growth occurs between pH 6.5–7.5, while growth is inhibited at pH 8.5 and above. The ideal temperature for growth is 25°C, though virulence varies with temperature—higher virulence is observed at 18°C, lower at 33°C, and no growth at 4°C. Salt concentrations above 0.7% can inhibit bacterial growth, and it thrives in both aerobic and anaerobic environments, though growth is slower under anaerobic conditions. 2. **Fungal Gill Disease (Mycosis)**: Caused by fungi such as *Plasmodium*, this condition affects various fish species, including grass carp, herring, and squid. The mycelium is generally straight, with limited branching, and grows primarily in tissue rather than blood vessels. Spores are typically 8 microns in size, and the hyphae can form net-like structures in certain species, leading to more severe damage. Fungal infections often occur in warm, nutrient-rich waters and can cause rapid fish death if left unchecked. 3. **Parasitic Gill Disease**: This condition is caused by parasites such as *Chinese sturgeon* and *Chinese quail*. Female parasites are long and cylindrical, with specialized hooks that attach to fish gills. High infestation levels can lead to gill damage, reduced respiration, and secondary bacterial infections. These parasites are commonly found in grass carp, herring, and eels, and they thrive in ponds with poor water quality. **II. Symptoms and Epidemic Trends** Bacterial gill disease causes symptoms such as lethargy, loss of appetite, and pale or discolored gills. Affected fish may float near the surface and show signs of respiratory distress. The disease is most prevalent when water temperatures exceed 20°C, peaking between 28°C and 35°C. Recent years have seen increased cases in intensively farmed species, leading to significant economic losses. Fungal mycosis typically targets young fish, causing rapid death due to gill blockage and impaired respiration. Outbreaks are common in warm, poorly maintained ponds, especially those with high organic content. Parasitic gill disease leads to visible white nodules on fish gills and can result in weight loss, reduced growth, and even death. Infestations are seasonal, with peak occurrences from April to November, particularly in areas using reservoir or river water sources. **III. Prevention and Control Measures** For bacterial gill disease, preventive measures include pond disinfection with lime, regular water changes, and the use of vaccines such as inactivated liver and spleen vaccines. Medications like Quanchipang Baoshengtang and chlorothalonil baits are used for treatment. For fungal infections, maintaining clean water and using bactericidal agents are essential. Parasitic infestations are managed with insecticides and careful monitoring. It is important to follow safety guidelines when using aquatic products, avoiding mixing with alkaline substances and ensuring proper application. Always wear protective gear and seek medical attention in case of accidental exposure.

Natural Extracts

What is Natural Extracts?

Natural extracts are biologically active compounds or mixtures extracted from various plants and animals or microorganisms in nature. These extracts contain a wealth of chemicals, Such as alkaloids, flavonoids, saponins, polysaccharides, volatile oils, collagen, proteins, peptides, enzymes, antibodies, antibiotics, Amino Acids, nucleic acids, enzymes, monosaccharides, oligosaccharides, polysaccharides, glycoproteins, resins, colloids, lignin, vitamins, fats, oils, waxes, alkaloids, volatile oils, flavonoids, glycosides, phenylpropanoids, organic acids, phenols, quinones, steroids And antibiotics, etc.
Natural extracts have received attention in several fields due to their wide range of sources and potential multiple uses. They can be used in the pharmaceutical industry as ingredients in medicines or health supplements; In the cosmetic industry, as a functional or active ingredient to improve skin health; In the food industry, as an additive or flavoring agent to increase the nutritional value and taste of food; In addition, they have different applications in the fields of agriculture, environmental protection and scientific research.
Extraction methods include solvent extraction method, ultrasonic extraction method, microwave extraction method, enzyme extraction method, supercritical fluid extraction method and microwave assisted extraction method, etc. The choice of which method usually depends on the nature of the substance to be extracted and the target requirements of the final product. With the development of technology, the extraction process is continuously optimized to improve extraction efficiency, reduce environmental impact and maintain the biological activity of the extract.

Natural Extracts, Chinese herb extract, plant P.E., Herb extract

Xi'an Day Natural Inc. , https://herb.dayqc.com