The gobbleguts has dark speckles and two separate dorsal fins. The males brood & incubate the eggs during summer months in its rather large oblique mouth.
Similar to the Scarlet Cardinalfish, I think the Gobbleguts are endemic to Australia waters (I could be wrong!). They can be found in sheltered shallow waters from southern QLD to central NSW. In Sydney, the best place to find these fellows is at Clifton Gardens during summer months.