(Sorry I can't help - I just wanted to say how gorgeous they look!)

I'd wait until spring as they are still in flower

Pretty problem.

I always divide mine , when they need them, in the spring when they are still dormant, or just starting to shoot. I also have flowers. when the water temp drops they will die back naturally. dont forget to remove the brown leaves to stop them rotting at the bottom of the pond.

I usually divide mine in the spring if they haven't flowered much the previous year or did not produce many pads. This I an indication that they are overgrown and require dividing. Yours looks just fine and really don't require it this time around if you have any doubts about doing it.

Thanks All, I will divid in the spring as the fish haven't much room to swim about.
The flowering has been non stop this year. :o)

another good indicator is if you have so much foliage they are 'climbing out of the water'. your photo shows they are starting to do this in the middle of the clump.

Your pond looks a wee bit small to have both a water lily and fish - just how big is it?

Well its round 6ft x 6ft x 3ft deep, if I could find a nice home for this one it would be nice for someone to have for their larger pond, then I could buy a small one to go in there with small leaves.
So anyone what it on here, its going begging LOL :o))

To big for our pond too and wrong end of the country but I'm sure someone would like try offering no your local Freecycle if no GoYer snaps up.