The Thornback Cowfish (Lactioria fornasini) is a slow-moving fish due to the hexagon shaped plate scales that cover it to create a box-like armour. As a relative of the pufferfish, the thornback cowfish produces similar toxins. Generating a powerful neurotoxin called ostracitoxin through their symbiotic relationship with bacteria. The ostracitoxin is carried in the organs and skin and can even be released into the water.
It is found in the tropical Indo-Pacific, Japan, and Hawaii where it feeds on invertebrates it hunts by blowing streams of water along the sand to expose its prey. This fish grows to between 6 to 9 inches long and can camouflage itself by changing color to blend with its environment. Like many cowfish, it is typically solitary, and males are territorial during mating season.
We photographed this thornback cowfish during a dive in Gili Air Indonesia. Read more in our post, A Scuba Divers Guide to Lombok, Indonesia.