i got one and lost one a month ago.... it was from a pretty unhealthy lfs that carries lotsa oddballs... it was 1" ... yes 1" ... that tiny.... and i guess it got beatened by the guppies in that tank x__x
They're from the family Platycephalidae (meaning flat head), and occur throughout the indo-pacific region. They're present along the entire coastline of Australia and are commonly used as food wherever they occur(they're actually very good). There are some species which DO get absolutely monster i.e. Platycephalus fuscus, which is reputed to reach over 100cm or approximatley 40 inches in length, at which time they look like a freakin' crocodile. Obligate piscivores, ambush predators as you can see, and don't generally move around much. What's really cool is that this family is so diverse that some species live in water over 1km deep, while others are happy to roam around in shallow mudflats in the tropics where the water's over 30 degrees celcius (close to 100 farenheit).
They're also quite morphologically diverse. The deepsea ones are generally smaller, but with blade-like spines along their body, and some rock-dwelling species have heads covered in bony spines and plates. Pretty cool animals really.