The unfortunate fishy had suffered from an untreatable swim bladder disorder that left him sitting upside down at the bottom of the tank, she said. Determined not to let their pet perish belly up, the desperate owners sought help from O’Shea. The pet caretaker managed to MacGyver a fin-tertube from tiny plastic tubing and T junctions normally used for air conditioning filters. She then weighed down the device with polystyrene so the scaly swimmer wouldn’t float to the surface — like ballast tanks on a submarine. Periodically adjusting the amount of polystyrene helped the goldfish swim to different levels in the tank, allowing him to see more of his home.