Which painting there are several.

I'm going to need a general dex check for you to quickly and carefully cut the picture from the frame without excessive damage.

And a strength check to pop the rivets that hold the copper plate to the plaque with the fish. 

To be specific there is a painting of the town, a painting of different fishing boats, and another with several fisher folk moving their catch.

You may also wish to consider where you will store the painting as they are rather large.