This is a find from Art Project Girl. She says it should take a half hour or so. Coupled with a book or video about fish, you could add on the needed time. Or you could give this to your sub in case they need something to fill in the time.
Art Sub Plans. I have created complete lessons in which all your sub has to do is read the slides and follow the directions. They are full of visuals and are created to be used with the most simple supplies. Pencils, paper and crayons are all your students will need to create imaginative works of art.
These are perfect for those emergency absences when you do not have the time to write detailed plans but want to leave quality plans for your subs.