Hoplostethus atlanticus, commonly known as the orange roughy, is a deep-sea fish inhabiting the Atlantic and Indo-Pacific Oceans. It is notable for its bright orange color, large eyes adapted for low-light environments, and exceptionally long lifespan, often exceeding 100 years. It dwells near seamounts and ocean ridges.

Hoplostethus atlanticus, commonly known as the orange roughy, is native to the deep-sea regions of the Atlantic, Indian, and Pacific Oceans. It is primarily found in the waters off the coasts of New Zealand and Australia, and also in the North Atlantic Ocean, particularly near Iceland and the Azores. This species is distributed across the continental slopes and underwater ridges, generally at depths ranging from 180 to 1,800 meters.

The orange roughy inhabits deep-sea environments characterized by cold temperatures, typically between 3 to 9 degrees Celsius. These areas often have low light levels due to their depth, and the water pressure is significantly higher than in shallower marine environments. The seafloor in these regions may consist of rocky substrates or soft sediments.

Hoplostethus atlanticus is a benthopelagic species, meaning it occupies the water column near the ocean floor. It is adapted to life in deep-sea conditions, with a slow growth rate and long lifespan, often exceeding 100 years. The orange roughy feeds on a variety of organisms, including crustaceans, fish, and squid. Its adaptations to the deep-sea environment include a swim bladder filled with wax esters, which helps maintain buoyancy despite the high pressures at depth.