Reach the point in the level just before entering the forest (with the Jackal Snipers), when the dropship arrives and blows up Johnson's Pelican. Kill all the enemies and jump in the water. You should see a few pale green or tan fish swimming. Keep jumping up and down to see where you are going. Move toward the waterfall. When you are on the edge, crouch and turn around toward where the fish were swimming. Back up until you can'tback up without falling. After toggling [Crouch] a few times, the water should disappear and the fish will be floating in air. If you have a loaded gun, you can shoot the fish (BR works best). The fish will slowly float through the air and to the ground. Note: This does not always work.