The orange roughy (Hoplostethus atlanticus), also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). The UK Marine Conservation Society has categorized orange roughy as "vulnerable to exploitation". It is found in 3 to 9 °C (37 to 48 °F), deep (bathypelagic, 180-to-1,800-metre (590 to 5,910 ft)) waters of the Western Pacific Ocean, eastern Atlantic Ocean (from Iceland to Morocco; and from Walvis Bay, Namibia, to off Durban, South Africa), Indo-Pacific (off New Zealand and Australia), and in the eastern Pacific off Chile. The orange roughy is notable for its extraordinary lifespan, attaining over 200 years. It is important to commercial deep-trawl fisheries. The fish is a bright, brick-red color, fading to a yellowish-orange after death.

Like other slimeheads, orange roughy is slow-growing and late to mature, resulting in a very low resilience, making them extremely susceptible to overfishing. Many stocks (especially those off New Zealand and Australia, which were first exploited in the late 1970s), became severely depleted within 3–20 years, but several have subsequently recovered to levels that fisheries management believe are sustainable, although substantially below unfished populations.