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65. Six-lined Soapfish (Grammistes sexlineatus)


A Six-lined Soapfish (Grammistes sexlineatus), also known as a Goldenstriped Soapfish, swims nervously underneath an overhang that serves as its shelter for the day. At night, these solitary hunters venture out of their crevices to hunt molluscs, crustaceans but mostly small fish.

Although seldom spotted by scuba divers, the Six-lined Soapfish is widespread throughout the warm waters of the Indo-Pacific, from the rich waters of the Red Sea and Africa's eastern coast to all the islands in and around Polynesia. The northernmost habitat of the Six-lined Soapfish is Japan's south coast. In the Pacific Ocean, this soapfish is found as far south as northern New Zealand. The main reason why not many scuba divers encounter this beautiful fish is that it spends most of the day hidden in dark crevices and nooks on rocky reefs, out of sight from most underwater photographers and marine wildlife videographers.

The number, length, colour, and continuity of stripes vary with age, with small juveniles only having two white stripes. When juveniles reach a size of 5cm/2 inches, they start to exhibit three lines. It is only when they grow larger than 8cm/3.2 inches that a total of six lines start to appear on their body. Old individuals sometimes exhibit dashes and dots instead of intact lines. Although this soapfish is often called a "six-lined" one, it is not uncommon to encounter adult fish that bear more than six lines. In fact, the number of lines on the Six-lined Soapfish can reach a total of nine. Adults can reach a total length of approximately 30cm/12 inches, making them a medium-sized fish.

Soapfish are named for their skin toxins, called grammistin. Small glands in the fish's skin release the powerful toxin when the fish perceives stress. This toxin, which resembles lathered soap, scares away predators due to its bitter and foul taste. If this soapy toxin is ingested at a high enough dosage, it can be lethal. Although the toxin is not used to kill prey, its main purpose is purely defensive. Scorpionfish species, which are ferocious predators of all kinds of fish, will immediately reject and spit out the caught soapfish after predation. Grammistin also has antibiotic and antimicrobial properties.


It was quite difficult to capture a single long shot (10 seconds or more) of this frantically moving fish. Therefore, I filmed it for several minutes while trying not to scare it. With all the short shots, I was able to create a composition of the best parts in post-production.

The best practice here is to keep the camera rolling and cut out all the unnecessary parts during editing. By acting as calm as possible and avoiding abrupt and jerky movements, the soapfish might become accustomed to the underwater videographer, which often results in better underwater images. Nervous or scared fish require a softer and calmer approach than most fish. If you act as nervous as your subject, you might run the risk of your subject hiding in a crack or crevice for a long time.

Filming location:

This short underwater videoclip has been filmed in Mauritius 🇲🇺

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