This is a large lake, and even though fishing is legal and free most places on the bank where access is allowed, it's easier to fish from a boat. You are not allowed to wade through reed zones, which limits access quite a bit, but you can catch fish from the bank.
You cannot use motorized boats, but rowing boats as well as kayaks and float tubes are allowed.
The lake is best known for its pike perch (zander) fishing in particular, but other species can be caught too.
There's boat launches and easy access at Frederikkes landeplads in Dronningholm (village), Ellehavegård (village), the bridge in Avderød Skov (forest), the bridge in Sonnerup Skov (forest), by Ll. Lyngby (village), by Pøle Å (stream), and from Ramløse harbor (village) and Ramløse Å (stream).