Domestic Standard Fin Koi

Domestic Standard Fin Koi (Cyprinus rubrofuscus) is a standard fin koi with traditional koi body and fin shape. Standard fins are proportional to the body and allow powerful, efficient swimming. These are the workhorses of the koi pond — robust, adaptable, and available in an excellent range of patterns and colors. This is a Domestic (USA-bred) koi — one of the most prestigious ornamental fish in the world, with a breeding tradition spanning over 200 years in Japan. Koi are bred in an extraordinary variety of named pattern classifications — Kohaku (red on white), Sanke (red and black on white), Showa (black with red and white), Utsuri, Bekko, Asagi, and many more — each with its own aesthetic standards and breeder community.

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.

Domestic koi are bred in the United States and represent excellent value — hardy, adaptable fish in a wide range of patterns and colors. While they may lack the ultra-precise pattern quality and luster of premium Japanese imports, domestic koi grow into beautiful pond fish and are ideal for aquarists building their first koi pond or stocking a large pond economically.

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