They will purposely swim into it's stream of bubbles & let it carry them e.g. rasboras like to swim against the flow of the filter (current). My 2 two-spot barbs & 2 albino corys are the ones keep playing in the bubbles /current.
I couldn't get it on video but they were all playing around it, less "current" from the filter so the Guppies.
If he's trying to stay in the filter current, that's where the water moves the most, . Plus goldfish love to swim around in the bubbles too! .. of music, I had Ludovico Einuadi playing all afternoon, very nice piano music Smiley. They might blow bubbles ever from time to time. The air pump in the middle blows out lots of bubbles and even the tiny tiny tetras have no problem with swimming around it. I'm also going to cut down on feeding to goldfish playing in filter bubbles once every two days, just to be safe. What you are witnessing with your fish is known as "flashing"- darting wildly around the tank, pacing the walls, doing tight circular motions in the water. Anyway I will continue monitoring Lucky until I go to work.