carotenoids 



Skin 



Examples of fish containing esterified astaxanthin in the skin are 

 Onchorhynchus nerka* * Saltno gairdneri, ^ Cyclopterus lumpus, ^ ^ the 

 marine dorado (Beryx decadactylus), and the rock cod (Sehastes 

 marinus). ^ ^ In the case oi Beryx decadactylus the term ** skin " includes 

 gills and mouth mucus. 



The taraxanthin-like xanthophyll (esterified) was noted in the fish 

 examined by Sumner and Fox ^ ^- ^ ** and Fox, ^ ^ viz. : the Pacific killi- 

 fish (Fundulus parvipinnis), the greenfish {Girella nigricans), the long- 

 jawed goby {Gillichthys mirabilis), the marine goldfish {Hypsipops 

 rubicunda) and the surf perch {Cymatogaster aggregatus). Recently 

 Fox and his associates ^ ^^ have reinvestigated the ** taraxanthin " of 

 Hypsypops rubicunda in detail. They resolved this fraction into a num- 

 ber of components, none of which is identical with taraxanthin. They 

 rather more closely resemble dinoxanthin {see p. 135), although one has 

 properties similar to lutein epoxide (see p. 17). An esterified neutral 

 xanthophyll pigment (probably taraxanthin) was found by Goodwin ^ " 

 in the sand eels Ammodytes tobianus and A. lanceolatus. Lonnberg'*^ 

 has noted the taraxanthin-like pigment and lutein in a considerable 

 number of species. Carotenoids have also been reported in the dorsal 

 skin of ells. ^ ' The known distribution of carotenoids in fish skin is 

 recorded in Table 31. 



Eyes 



In the large number of species examined by Lonnberg, ^ ^' ^ "^ the 

 eyes of only two were devoid of carotenoids : Gadus esmarkii, and 

 Squalus acanthias. Raja clavata was first thought to be in this class, but 

 was later found to contain traces. Wald ^ o noted the esterified taraxan- 

 thin-like pigment in the combined pigment-epithelia and choroid 

 layers of eyes of the sea robin (Prionotus carlinus), the black bass 

 (Centropristes striatus) and the sarp (Stenotomus chrysops). Beryx 

 decadactylus contains considerable amounts of astaxanthin in the iris 

 and sclera, ^ ^ but none in the retina. 



Flesh 



Carotenoids are not widely distributed in the flesh of fish, but 

 astaxanthin has been found in the flesh of Salmo salar, ^ i. 2 2 Coregonus 

 albula,^^^ Lophius piscatorus^^ and Onchorhynchus nerka.^ 



Liver 



The qualitative distribution in the livers of fish is recorded in Table 

 32. The only special comment which need be made here is that in 



* Anadromous fish are treated in this chapter for convenience. 



192 



