Abstract
The Pacific crevalle jack, Caranx caninus Günther, 1867, is a marine pelagic migratory fish species that usually inhabit shallow coastal water, including brackish and estuarine areas. The “pug-headed” abnormality in teleost fishes is characterized by an abnormal skeletal formation of the head, affected by an anteroposterior compression of the upper jaw, resulting in an abnormally shorter upper jaw concerning its lower jaw. In October 2016, an artisanal fisherman from Puerto Chale (Eastern Pacific, Mexico) captured a shoal of Pacific crevalle jack, where two of them presented morphological anomalies of pug-head, exophthalmos, opercle and anal fin. Both specimens’ size and weight were 69.9 and 59.3 cm fork length and 3200 and 2550 g, respectively. One of the individuals was a six-year-old female. A list of 58 cases of pug-headed marine fishes worldwide is provided and reviewed in this article. This study is the first report for the Eastern Pacific and also for wild specimens of Carangidae species. The causes of this abnormality remain uncertain and the main hypotheses were reviewed in this study. However, factors such as temperature, nutrition, salinity, oxygen dissolved, pressure, unspecified pollutants are not discarded. More studies in the future, including new techniques, must be done to clarify the causes of this abnormality.
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