Koi Losing Red/Orange Color: Diet, Light, and Genetics

Why Color Fades

• Diet: Carotenoids (astaxanthin, beta-carotene) from spirulina, krill, marigold meal, color-enhancing pellets.
• Intense sun: UV bleaches pigment; add 50–60% surface shade (lilies, floating plants, shade cloth).
• Genetics: Some lines (especially Yamabuki Ogon) naturally whiten with age.
• Health: Chronic stress or disease washes out color.

Action Plan

1. Switch to high-carotenoid food (e.g., Hikari Spirulina, Saki-Hikari Color).
2. Increase plant shade.
3. Test water—rule out ammonia/nitrite.
4. Accept that some color change is natural.

Stocking Note

15 koi in 1,200 gallons is heavy (≈1 inch per 10 gallons max). Monitor ammonia closely.