June 2012

Fish with glowing tails?

These very unusual young fish appeared beside our boat in Cairns Marina. Can you please tell us what they are?

Answer

Juvenile Diamond Trevally photographed in Cairns Marina by David and Brenda O'Brien.

These fish are young Diamond Trevally, Alectis indica.

Juveniles of this species have long trailing filaments from their dorsal, anal and pelvic fins. The filaments gradually reduce as the fish grows and no filamentous rays remain in adult specimens.

The juveniles of the closely related Pennantfish, Alectis ciliaris, also have long trailing filaments on the dorsal and anal fins, but lack filaments on the pelvic fins.

The Diamond Trevally grows to about 150 cm in length and is widespread throughout tropical and subtropical waters of Australia.

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.