This is just a test I did to check how to use particles within an animation.
The background has been hand painted in Gimp (2d). I also created 3 low poly models: a stone, a plant and a fish. Both the plant and the fish have been rigged. The texture for the stone, the plant and the fish have been taken from open source sites.
I have used four particles for this animation. The first two on the right are positioned in a way so that the bubble produced by the bottom particles target the particle above the scene (not visible in render). The same has been done for the particles on the left. The purpose of this test was to find a way to direct the bubbles without following any law of physics.