Grunts are typically inactive during day when they shelter near or under ledges. They feed mostly at dawn or dusk, moving out to feed on open sandy bottoms.
Haemulidae are divided into two subfamilies, Haemulinae and Plectorhynchinae (Sweetlips). These two groups differ greatly in diversity and distribution. Haemulinae which include most of the genera, are diverse in shape, ecology, and habitat. They have different feeding modes and prey items, and can occur from temperate reefs, coral reefs, sandy to muddy bottoms. Sweetlips are morphologically uniform, with an elongated body, a round head, and a subterminal mouth. Their colour and pattern change dramatically throughout their lives.
There are 19 genera and about 132 species of Haemulidae worldwide. Malaysia has 5 genera and 28 species of Haemulidae. There are 17 species of sweetlips and 11 species of grunters (Haemulinae from the Pomadasys genus only).