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Crystals create iridescent sheen: rainbow trout


Rainbow Trout / James Perkin.. / LicenseCC-by-nc-sa - Attribution Non-commercial Share Alike

The scales of a rainbow trout have a silvery shine due to guanine crystals.

"The scales of a rainbow trout, reflective yet translucent. The silvery lustre is due to crystals of guanine, produced in the body as a waste product. The tiny black speckles are pigment cells, and at intervals there are large clusters of these where the pigment is distributed right across each cell, instead of only in the centre; here we get the large black patches which produce colour changes in response to hormones released during the breeding season - hence the name rainbow trout. The overlapping scales form a waterproof armour which is flexible enough to allow for the flexing of the body during swimming." (Foy and Oxford Scientific Films 1982:87)
About the inspiring organism
Med_rainbowtrout Rainbow trout
Oncorhynchus mykiss (Walbaum, 1792)
Common names: Steelhead trout, Steelhead, Rainbow trout, Baiser, Baja California rainbow trout, Brown trout, Coast angel trout, Coast rainbow trout, Coast range trout, Hardhead, Kamloops, Kamloops trout, Kamchatka salmon, Kamchatka steelhead, Kamchatka trout, Lord-fish

Habitat(s): Wetlands
Learn more at
Some organism data provided by: FishBase
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

IUCN Red List Status: Unknown

Bioinspired products and application ideas

Application Ideas: Iridescent paints, textiles, cosmetics, buildings, or coatings.

Industrial Sector(s) interested in this strategy: Paints, textiles, cosmetics, building

Foy S; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
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