The Monterey Bay Aquarium announced Thursday that its largest ocean sunfish, a visitor favorite because of its massive size and unusual presence, was euthanized Thursday morning after a period of failing health.

Aquarium veterinarian Dr. Mike Murray and the husbandry team made the decision after a week during which the fish stopped eating and was increasingly unable to swim in the million-gallon Outer Bay exhibit where it was housed.

It grew from an initial size of 22 inches and less than 20 pounds to a length of 6 feet, 7 inches and a weight of 1,247 pounds