Domestic Ogon Koi
Domestic Ogon Koi (Cyprinus rubrofuscus 'Ogon') is a solid metallic koi variety — the term Ogon means 'gold' in Japanese and refers to a single-color metallic koi with no patterning. Ogon koi come in metallic gold (Yamabuki Ogon), metallic silver-white (Platinum Ogon), and other metallic single-color expressions. The clean, uniform metallic sheen of an Ogon is particularly striking in water, where it catches and reflects light throughout the pond. Domestic Ogon are US-bred — excellent quality at a more accessible price point than Japanese imports.
Feeding & Care Tip: Sera Koi Royal Mini Nature Food is ideal for smaller and younger koi. As fish grow, transition to Sera Koi Royal Medium Nature Food. Feed 2–3 times daily — only what the fish consume within 5 minutes. Koi are opportunistic omnivores that will also enjoy treats of watermelon, orange slices, and leafy greens placed at the pond surface. Stop feeding when water temperatures drop below 50°F (10°C) — koi metabolism slows dramatically in cold water and uneaten food will foul the pond.
Koi require a substantial pond — at minimum 1,000 gallons for a small group, with an additional 250–500 gallons per adult fish as they grow. A 24-inch depth minimum provides protection from temperature extremes and predators. Powerful biological and mechanical filtration is essential — koi produce enormous amounts of waste relative to their size. A UV sterilizer helps maintain water clarity. Regular partial water changes of 10–25% weekly maintain water quality. Predator protection — netting, motion sensors, or decoys — is strongly recommended as herons, raccoons, and other wildlife will target koi.
Keep in groups of at least three. Koi are highly social fish that thrive in the company of their own kind. The Ogon's solid metallic coloration creates a beautiful visual anchor in a mixed pond — it stands out clearly against both patterned koi and the pond environment. Domestic koi are hardy and adaptable, ideal for aquarists building their first koi pond.
Koi are among the longest-lived of all ornamental fish — well-kept specimens regularly reach 25–35 years, and the oldest documented koi lived over 200 years. They develop genuine recognition of their keepers over time and can be trained to hand-feed. The investment in a properly sized, well-filtered pond is rewarded with fish that become genuine long-term companions of extraordinary beauty.
Care & Ideal Parameters
| Difficulty | Moderate — pond setup required |
| Temperament | Peaceful — social pond fish |
| Typical Adult Size | 24–36 inches (60–90 cm) — some specimens larger |
| Min. Group Size | 3 minimum — 1,000 gallon minimum pond; 250–500 gallons per adult fish |
| Ideal Temp | 35–85°F (2–29°C) — ideal 65–75°F (18–24°C) |
| Ideal pH | 6.5–8.5 |
| Ideal GH | 5–20 dGH |
| Ideal KH | 3–15 dKH |
| Staple Food | Sera Koi Royal Mini Nature Food (juveniles); Sera Koi Royal Medium Nature Food (adults) |
| Treat / Supplement | Watermelon, oranges, leafy greens; Hikari Frozen Baby Brine Shrimp (juveniles) |
| Origin | Japan/USA (captive-bred — all ornamental koi are Cyprinus rubrofuscus) |
| Notes | Ogon = solid single-color metallic koi. Gold (Yamabuki) and silver/platinum (Platinum Ogon) are the most common expressions. Domestic = US-bred; excellent quality at more accessible price than Japanese imports. |
