A deep-bodied silver jack to 57 cm (22 in) whose front dorsal and anal rays trail out into fine filaments - short in adults, long enough in young fish to make them look like a different species entirely.
Those threads are the family signature and their purpose is disputed. In young fish they probably break up the outline and imitate the trailing tentacles of a jellyfish, which is a common strategy in juveniles of this family; in adults they are largely vestigial and wear down.
It hunts small fish and crustaceans over reef and sand, often in slightly turbid coastal water where the reef-edge jacks are scarce, and it is more solitary than most of the family.
The genus is a taxonomic minefield: several of these deep-bodied trevallies have been shuffled between genera repeatedly and are separated by fin ray counts rather than anything visible in the water, so a photograph identified to species should be treated as a proposal rather than a verdict.
- deep silver body with filaments trailing from the front of the dorsal and anal fins
- faint dark bars in young fish, fading with age
- steep forehead and a small mouth for a jack
- length up to 57 cm
Why it's threatened
Though this species is exploited, this is not considered to be a major threat on a global level at this time.
Threat classification from the IUCN Red List.
