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Hyperostosis - Swollen Bones
I recently caught a fish that had large lesions on its vertebrae. Are these due to a toxin or are they some kind of tumour?
Shane Hobson,
Newcastle, NSW
A leatherjacket vertebra showing hyperostosis. This bone is registered in the Australian Museum Fish Collection (AMS I.40274-001). View larger image.
The enlargement of areas of fish bones such as this is known as hyperostosis. Translated it simply means above normal bone growth.
Hyperostosis is known to occur in about 80 species of fishes across at least six orders and 20 families. Bone sites that are affected and how they grow appear to be fairly consistent within a species. View the hump on the head of a Snapper resulting from hyperostosis.
Why it happens, however, is unknown. It has been suggested that hyperostosis may be a response to pollution, or possibly a disease; however, evidence suggests that it has a genetic base.
If you are concerned because you found the bones on your dinner plate after a meal, don't be. Hyperostosis of the bones doesn't appear to have any effect on the edibility of the fish.
Mark McGrouther,
Collection Manager.
This page is a copy of the information published in the
Summer 1994-95 issue of Nature Australia Magazine (formerly ANH).
Further Reading
Smith-Vaniz, W.F., L.S. Kaufman & J. Glowacki. 1995. Species-specific patterns of hyperostosis in marine teleost fishes. Marine Biology 121:573-580.
