Pond Boss Forums INTRO Questions & Observations Normal grass carp behaviour?

Hi , firstly thanks for having me here ,
I’ve quite a large garden pond in the Uk , and have a grass carp in it , the fish in question is about 9 years old weighs I guess around 8 pounds ,
We’re coming on to winter here and the fish s dorsal fin and back are clear out of the water , it spends days like this , I appreciate there cold blooded but is this normal and will it dive as it gets colder ?

Thanks in anticipation