It is found in lowland and montane, tropical and subtropical and in the mountain rain forests up to 1,400 metres altitude in Borneo, Sumatra, Java, the Malay Peninsula, Singapore and southern Thailand.[1]
Assessors are one of the best reef aquarium fish.They are frequently seen hanging around in caves, overhangs and other shaded areas of the aquarium. The often do this upside down or vertically
They adapt by being very territorial
Their habitat are reefs. They are mainly found in the great barrier reef
The observation I made is that they seemed very curious about the reef. It seemed like it was trying to claim a cave in the reef before other fish did.