When I had only one bloodfin, I also had a bubble wand against the back glass in the tank.
As the bubbles were rising to the surface, I noticed the bloodfin would swim between the bubbles and sometimes would ride the upstream of the bubbles. It was not just an isolated incident, but I noticed this many times. Almost as if the fish was "having fun".
Later, as I bought fellow bloodfins, a few others would join in on the fish fun.
When I read the care sheets on these fish - I did not see this sort of information! 😉