2 finned tail

[Pam]

I have a koi born last year. It has the oddest tail - 2 fins, one vertical and one horizontal, sort of like the tail of an airplane. It looks like a star when it swims towards you. What would cause such a thing and should I be concerned?

 

[koiguy1969]

why be concerned if hes that old already? a genetic defect doesnt make him a bad fish. is he/she active and social?

 

[DrDave]

Do yu have a photo to share?

 

[Pam]

It is very active and social, although it does seem a bit more skittish than the others. I'm presuming it's because it doesn't swim as fast. Needs more time to dodge predators. Will try to get a picture of it.