Orange Roughy - Physical Description

Physical Description

The orange roughy is not a vertically slender fish. They turn orange after death, but are red while living.

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 15-18 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 centimeters (30 in) and a maximum weight of 7 kilograms (15 lb). The average commercial catch size is commonly between 35 and 45 cm in length. The name orange roughy was renamed from the less gastronomically appealing slimehead through a US National Marine Fisheries Service (NMFS) program during the late 1970s, which identified (then) underutilized species that should be renamed to make them more marketable.

Due to its longevity, the Orange Roughy accumulates large amounts of mercury in its tissues, having a range of 0.30 - 0.86 ppm compared with an average mercury level of 0.086 ppm for other edible fish. Based on average consumption and the recommendations of a National Marine Fisheries Service study, in 1976, the FDA set the maximum safe mercury level for fish at 1 ppm. Regular consumption of Orange Roughy can have adverse effects on health.

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