Hi Sealan
Yes there are many websites you can go and have a look at the website of Pieter at this
address
http://koi4u.co.za/
There are many others I also like to go to Koivet of doc johnson
Ihttp://www.koivet.com/index.html
think your problem is a spot of carpox normal for this time of year and it will go away by itself.
Try to post a photo and I am sure you will get a lot of reply's