Polynemus is a genus of threadfins (family Polynemidae). Goatfish, sharks, groupers, baracudas, threadfins, lizardfish and rabbitfish also occur in lower frequency. This attribute allows threadfins to enter estuaries and even rivers. Their habit of forming large schools makes the threadfins a reliable and economic catch. Unlike other threadfins this species has a small proportion of the population which are hermaphroditic. King threadfins in the process of transitioning are most frequently recorded from June to September. Threadfins are silvery grey perciform fish of the family Polynemidae. In Hawaii, sixfinger threadfins are the subject of commercial open-ocean cage mariculture. Noted for being euryhaline, threadfins are able to tolerate a wide range of salinity levels.