The Lampris guttatus, commonly known as the opah or moonfish, is a large, deep-bodied pelagic fish found in temperate and tropical oceans. It is known for its striking iridescent body with vibrant red fins. Unique among fish, it is capable of whole-body endothermy, maintaining a warmer body temperature than the surrounding water.

Lampris guttatus, commonly known as the opah or moonfish, is a pelagic fish species found in oceans worldwide. It is primarily distributed across the Atlantic, Pacific, and Indian Oceans, particularly in temperate and tropical waters. Opahs are found in regions including the eastern and western coasts of the United States, the waters around Hawaii, the North Pacific, the Mediterranean Sea, and the coastlines surrounding South Africa and Australia.

Opahs typically inhabit the open ocean, dwelling at depths ranging from the surface to about 400 meters (1,300 feet). They prefer temperate to tropical oceanic conditions, where water temperatures align with their physiological needs. These fish are known for their unique thermoregulation abilities, allowing them to maintain a body temperature higher than the surrounding water, enabling them to thrive in cooler deep-sea environments.

Lampris guttatus occupies a niche as a mid-water predator in the pelagic zone. They feed on a variety of prey, including small fish, squid, and crustaceans. Opahs are known for their agile swimming capabilities and are an important part of the marine food web, serving as prey for larger predatory fish and marine mammals. Their ability to regulate their body temperature gives them a competitive advantage in deep and cold waters, where they can be more active hunters compared to other fish that lack this adaptation.