This little fish suffered from swim bladder disease, which caused the tiny guy to struggle keeping himself upright.
His owner created a little device to keep the fish upright by offloading and redistributing its weight, and it does the whole "right-side up" thing for him.
Ok. First of all, whoever this owner is, I think we need to convince him to be ruler of the world, because if he's willing to figure out the logistics of this little device and put it together all for a FISH, then imagine what he could do for humanity.
I don't generally pick up on fish body language very well, but this little dude looks pretty happy. Life had to have been kind of rough for him- not only would eating be hard, he had to stare up other fish's noses all the time, and that would be a drag.