Orange Roughy

The orange roughy, red roughy, or deep sea perch, Hoplostethus atlanticus, is a relatively large deep-sea fish belonging to the slimehead family Trachichthyidae . The Marine Conservation Society has categorized orange roughy as vulnerable to exploitation. It is found in 3 to 9 C 37 160 to 48 160 F deep bathypelagic, 180 to 1,800 metres 590 to 5,900 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, with lifespans up to 149 years determined by scientific methods. It is important to commercial deep trawl fisheries. Actually a bright brick red in life, the orange roughy fades to a yellowish orange after death.

Like other slimeheads, the orange roughy is slow-growing and late to mature, resulting in a very low resilience. They are extremely susceptible to overfishing because of this, and many stocks especially those off New Zealand and Australia, which were first exploited in the late 1970s have already crashed recently discovered substitute stocks are rapidly dwindling. The flesh is firm with a mild flavour it is sold skinned and filleted, fresh or frozen.

The body is deep, that is, it is not a vertically slender fish. The rounded head is riddled with muciferous canals part of the lateral line system , as is typical of slimeheads. The single dorsal fin contains four to six spines and 15 to 19 soft rays the anal fin contains three spines and 10 to 12 soft rays. The 19 to 25 ventral scutes modified scales form a hard, bony median ridge between the pelvic fins and anus. The pectoral fins contain 17 to 20 soft rays each the pelvic fins are thoracic and contain one spine and six soft rays the caudal fin is forked. The interior of the mouth and gill cavity is a bluish black the mouth itself is large and strongly oblique. The scales are ctenoid and adherent. The lateral line is uninterrupted, with 28 to 32 scales whose spinules or ctenii largely obscure the lateral line's pores. The eyes are large.

The orange roughy is the largest known slimehead species at a maximum standard length a measurement which excludes the tail fin of 75 160 centimeters 29.5 160 in and a maximum weight of 7 160 kilograms 15 160 lb . The average commercial catch size is 30 to 40 centimetres 12 to 16 in .

Orange roughy are generally sluggish and demersal they form aggregations with a natural population density of up to 2.5 fish per square meter, now reduced to about 1 per square meter. These aggregations form in and around geologic structures, such as undersea canyons and seamounts, where water movement and mixing is high ensuring dense prey concentrations. The aggregations are not necessarily for spawning or feeding it is thought that the fish cycle through metabolic phases active or feeding and inactive or resting and seek areas with ideal hydrologic conditions to congregate during each phase. They lose almost all pigmentation while inactive, during which time they are very approachable. Predators include large deep-roving sharks, cutthroat eels, merluccid hakes, and snake mackerels.

When active, they feed primarily on zooplankton such as mysid shrimp, euphausiids, amphipods and other crustaceans adults also take smaller fish and squid. The orange roughy's metabolic phases are thought to be related to seasonal variations in prey concentrations. The inactive phase conserves energy during lean periods.