Not furry, but we like them anyway.
Butterfly Koi
Cyprinus rubrofuscus
Also called Longfin koi, Dragon carp, Dragon koi, Onagagoi, Hire naga nishikigoi
From Japan and the United States. Japanese breeding at the Saitama Prefectural Fisheries Experiment Station crossed a long-finned Indonesian carp with koi in the early 1980s, and the name butterfly was coined in the US.12
At a glance the quick version
Looks how to spot one
Scaled or partly scaled koi with very long fins
A koi with dramatically lengthened fins and tail that trail behind it like ribbons or wings. The fins are many times longer, relative to the body, than on standard koi, which gives the fish a slow, floating style of swimming.13
Personality what they are like
Calm and easygoing. Like other koi it can learn to recognise the people who feed it and may come to take food from the hand.12
Daily activity how busy a day looks
Swims more slowly and gracefully than standard koi, so it appreciates a pond without strong currents and room to glide.1
Grooming and care the hands-on bits
Needs clean, well-filtered water and a large, deep pond. Koi do best at about 15 to 25 C and should not be fed when the water falls below about 10 C.12
Home where they are happiest
An outdoor pond fish. Wikipedia suggests a depth of about 90 cm and a lot of water per fish, while general koi guidance calls for at least 1 m depth, more in cold-winter climates, with a pump and filter.12
Food basics what goes in the bowl
An omnivore. Feed a balanced, protein-rich koi food with some vegetables and occasional treats such as earthworms or shrimp.1
Company who they like around
Sociable and fine in a group with ordinary koi, which share the same care.1
The story where it all began
In 1977 Crown Prince Akihito suggested crossing a long-finned Indonesian carp with Japanese fish, and the Saitama station began breeding in 1980, producing the first long-finned koi two years later. Randy LeFever, son of US koi breeder Wyatt LeFever, gave them the name butterfly koi, and they became very popular in North America.1
Fun facts for the dinner table
- 1
Their fins can be 500 to 1000 percent longer, relative to the body, than a standard koi's.1
- 2
The idea of breeding them came from Crown Prince Akihito, later Emperor of Japan, during a 1977 visit to a fisheries station.1
- 3
They are nicknamed American koi because they are so popular in North America.1
- 4
The butterfly name compares their long fins to butterfly wings.3
Recognised by the official bits
- Associated Koi Clubs of America (AKCA)
- Introduced separate judging standards for butterfly koi (June 2006)1
- Zen Nippon Airinkai (ZNA) / UK Koi Judges Association
- Not judged in their competitions1
The care rhythm a typical week and year
A typical home-care rhythm for a Butterfly Koi. A starting point, not a vet's advice.
- FeedingOnly in the warm seasonevery day
- Pond checkevery day
- Water testevery 2 weeks
- Filter cleanevery month
Owner questions the things everyone asks
How often should I feed my Butterfly Koi?
Feed your Butterfly Koi once a day during the warm season, but stop when the water temperature drops below about 10°C. Follow the food label for portion sizes and check with your vet for a schedule that suits your pond.12 Pet Wiki plan
What does a Butterfly Koi eat, and what should it never eat?
They enjoy a balanced, protein-rich koi food with vegetables and occasional treats like earthworms or shrimp. What they should never eat varies by individual; ask your vet for a list of unsafe foods.1
How much space does a Butterfly Koi need?
They need a large, deep outdoor pond, at least 90 cm deep, with 1 m or more recommended in cold climates. Provide plenty of water per fish and a gentle current to match their graceful swimming style.12
What temperature, light or water does a Butterfly Koi need?
Keep the water between 15 and 25°C, and stop feeding below 10°C. They need clean, well-filtered water in an outdoor pond with natural daylight; for specific lighting needs, ask your vet.12
How often should I clean a Butterfly Koi's home?
Check the pond daily, test the water every two weeks, and clean the filter monthly. Regular partial water changes also help; ask your vet for a full cleaning routine tailored to your setup. Pet Wiki plan
Can a Butterfly Koi live with others?
Yes, they are sociable and do well in a group with ordinary koi. They are calm and easygoing, and may even learn to take food from your hand.1
How long does a Butterfly Koi live?
With good care, they can live 25 to 35 years. A spacious, clean pond and a proper diet help them reach their full lifespan.1
Can I handle a Butterfly Koi?
They are not meant to be handled; their delicate fins and body can be stressed by touch. Enjoy watching them and feeding by hand, but avoid picking them up. If handling is necessary, ask your vet for safe techniques.12
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Pet Wiki's own starting care plan. A friendly guide, not a vet's advice.
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Where this comes from
Every fact on this page has a numbered source. Spotted an error? [email protected].
- Wikipedia: Butterfly koi en.wikipedia.orgused for names, origin, history, fins, colours, lifespan, care, diet, recognition, fun facts
- Wikipedia: Koi en.wikipedia.orgused for ancestry, temperature, pond depth, feeding, hand-feeding behaviour
- Wikipedia (German): Koi de.wikipedia.orgused for name meaning, popularity with pond owners
Checked 2026-09-30. Text is written in our own words from these sources.