Discoloration could be acanthosis nigricans.

Well, the acanthosis nigricans was already there.

Acanthosis nigricans is a hyperpigmentation of the skin.

- We should do an ACTH stimulation test and check his skin for acanthosis nigricans.

They are: marlins,18 of which there are nine species (Tetrapturus angustirostris, T. belone, T. pfluegeri, T. albidus, T. audax, T. georgei, Makaira mazara, M. indica and M. nigricans), with one or more species found in every ocean; sailfishes, with two species, Istiophorus platypterus, formerly restricted to the Indian and Pacific Oceans but now found in the Mediterranean Sea where it entered via the Suez Canal, and I. albicans, found in the Atlantic Ocean and migrating in the Mediterranean Sea; and swordfish (Xiphias gladius), found in the Atlantic, Indian and Pacific Oceans, the Mediterranean Sea, the Sea of Marmara, the Black Sea and the Sea of Azov.