"Diamond Fish" is another name for the diamond-shaped, Pacific Halibut. The largest of the known flatfish, the Pacific Halibut can grow to 9 feet in length and weigh from 500 to 700 pounds. Their range includes the coastal waters of the northeast Pacific from northern California to the Gulf of Alaska to the Aleutian Island chain where they have been fished for hundreds of years by Native Americans on the Pacific Coast. The oldest halibut on record, male or female is 55 years-old, though females outlive males.