The chemical and physical properties of collagen proteins are different in tissues such as
skin, swim bladder and the myocommata in muscle (Mohr, 1971). In general, collagen
fibrils form a delicate network structure with varying complexity in the different
connective tissues in a pattern similar to that found in mammals. However, the collagen
in fish is much more thermolabile and contains fewer but more labile cross-links than
collagen from warm-blooded vertebrates. The hydroxyprolin content is in general lower
in fish than in mammals, although a total variation between 4.7 and 10 % of the collagen
has been observed