The Slate Sweetlips (Diagramma labiosum) is a tropical fish species that belongs to the ‘Sweetlips’ family of fishes Haemulidae. This species has been recorded from Perth in Western Australia around the north to Sydney in New South Wales. However, it is more commonly found in the warmer water of Queensland, the Northern Territory and the northern region of Western Australia. Juveniles are yellow/white in colour and have thick black stripes running along the ridge of the dorsal fin and along the lateral line. As they get older the stripes fail and adults are a blue/grey colour all over. Adults are generally found in small aggregations on deep tropical reefs or wrecks.
This species is also commonly referred to by fishers as ‘Mother-in law fish’ as it’s not considered to be a good eating species. The Slate Sweetlips (Diagramma labiosum) grows to a maximum length of approximately 1 metre.