Sexual dimorphism in marbled flounder

What is it about?

This paper explains the difference in external morphology between male and female of marbled flounder. Fishermen discriminate male and female fish by touching the non-eye side, which is usually rough in males and smooth in females. This difference was caused by the difference in scale morphology: scales of male fish have spines but those of females do not. The rough skin of male was thought to be important for spawning, namely attaching to female fish.

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Why is it important?

This paper first revealed the sexual difference in external morphology of pleuronectid flatfishes. The results would be applicable to congeneric species. It is also helpful to sample male or female fish from market specimens.