Fish Profiles Dusky Flathead

Dusky flathead (Platycephalus fuscus) inhabit estuarine and inshore coastal waters from Cairns in far north Queensland to the south west Victorian coast. Growing to 1.5 metres in length and over 10 kilograms in weight they are the largest and most commonly targeted flathead species by recreational anglers.

Also known as mud flathead, estuary flathead, black flathead and lizards, dusky flathead range in colour from fawn with dark spots and blotches to dark brown, almost black with white spots. Dusky flathead are a rather strange looking fish with a triangular shaped head that is rounded at the mouth and gills and an elongated body tapering from the head down to the tail.

Dusky flathead start life as eggs that are spread along the coast by currents and tidal movement. Juveniles smaller than 10 centimetres in length appear in bays, estuaries and adjacent surf beaches 4 -10 weeks after spawning. They may then make their way up stream as far as brackish water.

It is estimated that dusky flathead can reach a length of 18 cm in twelve months. The spawning period is known to occur between September and March depending on geographical location. Female dusky flathead are known to be reproductively active between November and March and males between September and March. During the spawning period dusky flathead will migrate towards the lower reaches of estuarine systems to begin the spawning process.

Female dusky flathead are believed to reach sexual maturity at a length of 57 centimetres where as males would be at their sexual reproductive peak at 32 centimetres in length. Most flathead over 60 centimetres in length would be female and it is a growing trend for recreational anglers to release any fish over that length. In days gone by large flathead would be slaughtered and their heads nailed to trees, sort of like a trophy shrine. Thankfully commonsense has prevailed and recreational anglers know realise the importance of protecting valuable breeding stocks of large female dusky flathead.

The diet of dusky flathead will inevitably vary from season to season and in differing geographical locations Mainly consisting of small fish, especially juvenile mullet, crabs, saltwater yabbies, squid and octopus. During the warmer months in NSW and Victoria  schools of juvenile mullet (poddy mullet) start to appear over estuarine sand flats and school and king prawns start their migratory movement from the estuaries to the open ocean the flathead’s and make up the majority of the dusky flsthead’s diet. An ambush predator by nature often burying themselves under a fine layer of sand waiting for prey to get close enough to launch a lightning fast attack.

Flathead numbers have been greatly reduced in the last 30 years or more by increased demand as a marketable species. Recreational anglers have seen the importance of the dusky as a valuable sport fishing target and catch and release is now very common. In Queensland’ there has been an upper maximum size restriction placed on the species meaning any fish over a certain length must be released. Hopefully other states will follow suit. Lower maximum legal lengths have also been increased to give the species a chance to spawn and conserve stocks.