Blacktails are medium-size, oval, silver fish. Their tails are not black as their name suggests, but they do have a large black spot on each side of their caudal peduncle. As juveniles, they have 8 to 10 pale vertical bars on their sides, but these fade with age.
They are omnivores, equipped with both strong molars and sharp incisors to help process a variety of foods including red and green algae, starfish, urchins, snails, bivalves, polychaetes and sea squirts.
Blacktails inhabit many shallow environments on the South African and Namibian coasts. They are highly resident, and adults rarely leave their preferred home region.
Blacktails are hermaphrodites, and unlike many other hermaphroditic fish species, there is no relation between their age or size and their sex. In fact, many blacktails are able to be both male and female simultaneously.