This is a quote
MNRF direction on what anglers must do with their fish when there is no legal possession limit is as follows:
“If an angler catches a fish that cannot be legally possessed (e.g., during the closed season, prohibited size, exceeds the catch and possession limits), the fish must be immediately released at the place and time of capture. This includes fish that may be injured during catch. This information is available to anglers on page 11 of the 2021 Ontario Recreational Fishing Regulations Summary.”
If an angler catches a fish that cannot be legally possessed (e.g prohibited size), the fish must be immediately released at the place and time of capture
the way I read it you can’t take a photograph of an undersized Muskie or Walleye.