I. Size Range and Varietal Differences
Common Domestic Koi Fish
Ordinary Varieties: Generally, the body length ranges from 30 to 50 centimeters. When raised in fish tanks, due to space limitations, the body length is mostly maintained at around 40 centimeters.
High-Quality Bloodlines: Precious varieties such as Japanese Kohaku and Taisho Sanshoku can reach a body length of 70 to 90 centimeters in 3 years when raised in ponds, with an annual growth of approximately 20 to 30 centimeters.
Giant Varieties
Ryukin Koi: A specially selected variety, the adult body length can reach 80 to 100 centimeters, and the tail spread width exceeds 40 centimeters.
Record Cases: A koi fish with a length of 1.08 meters was once raised in Shandong, China. Japanese documents record that there was an individual with a length of 1.5 meters before World War II (needs verification).
II. Growth Stage Data
Larval Stage (0 - 1 Year Old): The daily growth is 0.5 to 1 millimeter, and the body length can reach 15 to 20 centimeters at 6 months of age.
Rapid Growth Stage (1 - 5 Years Old): The annual growth is 15 to 25 centimeters, and the body length can reach 60 to 80 centimeters at 5 years of age.
Mature Stage (After 5 Years Old): The growth rate drops to 2 to 5 centimeters per year, and individuals at 10 years of age generally reach a body length of 70 to 90 centimeters.
III. Quantitative Analysis of Key Influencing Factors
Water Volume
For every 1 cubic meter increase in water volume, the annual growth rate increases by approximately 8% (based on comparative experiment data).
Ideal Breeding Density: < 1 fish per 200 liters of water. Over - density breeding can lead to a growth inhibition of more than 30%.
Nutrition and Water Temperature
Protein Requirement: Larval koi fish need feed with more than 40% protein, while adult koi fish only need 35% protein in their feed.
Optimal Water Temperature: The metabolic efficiency is the highest when the water temperature is 24 - 26°C. When the water temperature is lower than 18°C, the growth rate decreases by 50%.
Genetic Potential
The offspring of SS - grade parent fish grow 20% - 40% faster than ordinary varieties, but professional breeding techniques are required to achieve this.
IV. Special Breeding Techniques
Environmental Control: The use of a circulating water system combined with UV sterilization can reduce growth stagnation caused by diseases.
Feed Formula: Adding spirulina, astaxanthin, etc., can improve the body color and at the same time promote growth by 15% - 20%.
If specific breeding parameters for certain varieties or disease prevention and control plans are needed, more detailed explanations can be provided.