This seal shows a fish which Evans identified as a parrot wrasse, also known as the skaros. He thought the fish was shown in perspective, perhaps because of the arrangement of plants around it.
Bibliography
Evans, Arthur. 1921. The Palace of Minos at Knossos, I, p. 677, fig. 498
Myres, John (ed.). 1936. British Archaeological Discoveries in Greece and Crete 1886-1936, p. 28
Hughes-Brock, Helen and Boardman, John. 2009. Corpus of Minoan and Mycenaean Seals VI: Oxford, the Ashmolean Museum, no. 257