Hello,
these fish can even handle German winter temperatures, so winter in Greece will be no problem.
The Origin is the same as goldfish and some big carps/cyprinids which are crossed in some Koi-Varierities.
They allso are kept much better in ponds then in aquariums because of their way of eating.
(sorry that I wrote in english, I´m just too lazy to use my brain hardly to write that in Greek
)
