South African Koi Keepers Society: http://www.sakks.co.za 
South African Koi Traders Association: http://www.sakta.co.za
Koi Fish Ponds: http://www.fantasticfihpond.com
Very good Forum and source of information: http://www.koiphen.com/forums 
Pan Intercorp: http://www.koi.com 
General Info: http://www.chilternkoi.nildram.co.uk 
Koi Vis: (Afrikaans): http://myweb.absamail.co.za/hoffman.m6
Koi health: http://www.koivet.com