The western wirrah has a greenish-brown colouration with numerous black-rimmed blue spots over the body surface and fins which form lines over the head. The fins are dusky with a bluish tinge and thin pale blue edges. Juveniles of this species have dusky bands radiating from the eye. It is a rounded fish with a large protrusible mouth and thick skin. Similarly to other species in the Serranidae family, western wirrah are protogynous hermaphrodites, maturing first as females, then after spawning one or two times they change sex, spawning thereafter as males. The western wirrah grows to a maximum length of 50 centimetres.
The western wirrah occurs in caves and crevices in exposed coastal reef areas to depths of 100 metres, from Shark Bay, WA to Ceduna, SA. Juveniles commonly live in shallow rock pools, and are also found in moderate surge zones. The western wirrah hunts nocturnally, feeding on crustaceans and small fish.
Other common names include: Rottnest boot, wirrah cod.
Occurrence at the Busselton Jetty:
A shy, nocturnal species, the western wirrah is rarely observed from the underwater observatory. When it is spotted it is often moving from one cryptic hiding place to another.