Found this on the net and says they have even longer barbells then other koi.
The Butterfly koi is similar to the traditional Koi, but is equipped with long and flowing decorative finnage. The finnage resembles the delicate wings of a butterfly, hence them name. Many breeders and Koi keepers do not consider the Butterfly Koi a true Koi, since it is a hybrid.
The first Koi fishes were developed in Japan during the 19th century, but the Butterfly Koi has a history no longer than a few decades. The Koi fish is sometimes viewed as a Goldfish, but this is not true. Both Koi and Goldfish are domesticated versions of a wild carp and they are closely related, but the goldfish was developed in China while the Koi was breed in Japan.
In Japan, the term Koi is used for ordinary carp fishes and the term “Nishikigoi” is more accurate if you want to refer to domesticated ornamental carps. Koi was however the word that managed to make its way in to the English language, and the international name for this type of fish is therefore Koi. Koi keeping did not really catch on outside Japan until the later half of the 20th century when airfreight and plastic containers made it possible to transport Koi fish to other parts of the world.
In the 1980’s, new variants of the traditional Koi began to show up in the aquarium trade under names such as Dragon carp, Longfin Koi and Butterfly Koi. Traditionally, the different Koi variants were distinguished from each other based on scalation, coloration and pattering. These new variants did however distinguish themselves from all the earlier Koi variants by having unusually long and flowing fins.
The true origin of the Butterfly Koi has been debated. Most aquarists agree that it is a hybrid formed by crossing ordinary Koi with some type of Asian carp, e.g. Indonesian long fin carp. It is possible that different lines of Butterfly Koi actually hail from different origins, since many different breeders can have sought to create more ornamental Koi fishes. Some people even suggest that Butterfly Koi is the result of breeding Koi with Goldfish, but this is not very likely.
Due to its hybrid origin, Butterfly Koi is seldom appreciated at traditional Koi shows. It does however have a strong fan club and many people love these fishes regardless of genetics. Butterfly Koi comes in many different color patterns, just like the traditional Koi. White, orange, yellow or combinations of all tree colors are common. Except from having long and flowing fins, the Butterfly Koi can also be distinguished from traditional Koi by having somewhat longer barbells and bigger nares.
Small Butterfly Koi is sometimes kept in aquariums, but this fish is much more popular as a pond fish and can reach a size of 36 inches. It is considered an easy fish to care for and it has a peaceful temperament. Ideally provide your Butterfly Koi with a pond of at least 1,000 gallons. The Butterfly Koi likes to nibble at the roots of plants and sturdy plant species are therefore recommended. You should also protect the base of the plant by encircling it with large stones or similar. The Butterfly Koi will endure temperatures from 33 to 90° Fahrenheit. Keep the pH in the 6.8-7.2 range and the dH between 2 and 12. You can feed your Butterfly Koi pellet food as long as you make sure that it is of high-quality and contains no more than 30% protein.