We went to the hardware store and got a bunch of sticks they give you to stir your paint. You could use craft sticks but the bigger the better. The larger sticks are easier to hold and they do not break.
Then we glued a fish to each of the sticks until we had a whole school of fish. The children scattered around the room with their fish and when the music began they could walk around while the fish moved up and down with the music. Initially you may find that it helps if you are quietly singing the music as it plays "Down, Up, Down, Up, Down and hold. . ." etc through-out the music. It is one thing to do the ups and downs with visuals. It is much more difficult to hear them.
To make the activity even more fun we decided not to do the downward music "of the bubbles" but instead we told the children that for today the bubble music would represent "dinner time" for the fish. We put a chair in the center of the room and had a child stand on the chair with a jar of bubbles. He would blow the bubbles into the air and the fish would all come and "eat" them. With a large class it was necessary to have 3-4 people feeding the fish.
Here are some fish you could print out for this activity or the kids can draw their own. These are the same fish used in Part 1 so the kids will associate these fish with this piece of music.