The Drysdale grunter (Syncomistes rastellus) is a species of fish in the family Terapontidae. It is endemic to Australia, where it occurs in the Gibb and Drysdale Rivers, coastal rivers in northern Western Australia. It is a herbivorous species which grazes on filamentous algae and prefers the main river channels rather than the tributaries, it also prefers flowing water of varying turbidity and substrate.[1]