Goldenstriped Soapfish

The goldenstriped soapfish (Grammistes sexlineatus), commonly referred to as the lined soapfish, golden-striped bass, radio fish, sixline soapfish, six-lined perch, or white-lined rock cod, belongs to the family Serranidae, which includes groupers, within the subfamily Epinephelinae. This species exhibits a broad distribution across the Indo-Pacific region.

Grammistes sexlineatus is a medium-sized marine ray-finned fish, capable of reaching a maximum length of 30 centimeters. Its body is predominantly dark brown, marked with up to six horizontal lines that range in color from white to yellow. The number of lines corresponds with the fish's maturity. Juveniles display yellow to white spots on a dark background until they reach approximately 17.5 millimeters in size, at which point the spots begin transforming into lines. By the time the fish reaches 5 centimeters in length, it typically has three horizontal lines, with the full six distinctive horizontal lines appearing at about 8 centimeters. In adult specimens approaching maximum size, these lines tend to fragment into smaller strokes and points.

This species is well-distributed across the tropical and subtropical waters of the Indo-Pacific, from the eastern coast of Africa to the oceanic islands of the Pacific, including regions such as Hawaii (🇺🇸 United States), the 🌊 Red Sea, southern 🇯🇵 Japan, and northern 🇳🇿 New Zealand. It inhabits coastal rocky and coral reef environments at depths ranging from shallow waters to 40–50 meters.

Individuals of Grammistes sexlineatus are generally solitary within their reef habitats, often hiding in crevices and displaying heightened activity during nighttime. Similar to other members of the subfamily Grammistinae, this species secretes a toxin known as grammistin from its skin, a substance that resembles lathered soap and is the origin of its common name, "soapfish." Due to the unpleasant and bitter taste of its flesh, it is not targeted as a food fish.

The first formal description of the goldenstriped soapfish was provided by Swedish naturalist Carl Peter Thunberg (1743-1828) in 1792, originally classified as Perca sixlineata, with the type locality identified as the East Indies or 🇯🇵 Japan.