The body is covered in finely ctenoid and there is a continuous, smoothly curved lateral line.

The caudal fin is darker towards the base and slightly dusky along its edge, particularly on the upper lobe.

[3] Adult Fortescue grunters are found rocky pools and the slow-flowing sections of streams, as well as in schools at the base of small waterfalls.

The main threats are the degradation of the drainage systems by overgrazing, pollution from mining and introduced alien specs such as mollies and the crayfish Cherax quadricarinatus.

[1] The Fortescue grunter was first formally described as Therapon aheneus in 1963 by the Dutch ornithologist and ichthyologist Gerlof Mees (1926-2013) with the type locality given as Millstream Pool.