The he Devil Scorpionfish (Scorpaenopsis diabolus) is also known as the False Stonefish. They are extremely well camouflaged and as can be seen in the image below are hard to spot. As with all members of the scorpionfish family, they have poison glands for protection in their dorsal and pelvic fins.
The Devil Scorpionfish is a rather ugly unpleasant looking fish and its species name of diabolus which roughly means devil in Latin, is derived from its rather frightening looks. Their colouration is extremely variable and they take on the colours and textures of their surroundings. The skin is warty and full of small flaps. As they are immobile most of the time, algae and other organisms tend to grow on them adding to their camouflage.
They have a typical Scorpionfish shape with a proportionally large head and mouth. They have a very distinctive hump shaped back which once one gets to know the shape of, helps to spot them. The pectoral fins are rounded and are colorful , resembling a fold out fan but are usually folded back with the bright colours concealed. The tail is small in comparison to the head and they are poor swimmers.
Scorpionfish have a cuticle of skin that covers the body and this is changed every few weeks giving them a resilience against parasites. It is thought by some that they change their texture and colour to suit their surroundings on these cuticle changes. As they near a skin change so the colours become less vibrant and they appear more dull.
Over their eyes they have a flap of skin which helps to break up the shape of the eye. If one is ever in doubt as to whether one is looking at a Stonefish or a Devil Scorpionfish , look at the eye and if it has a flap on the eye it is a Devil Scorpionfish.
IN THE WILD
The Devil Scorpionfish are remarkably hard to spot. Once one becomes attuned to their shape it does get easier. The shape of the humped back and large head and the tail curling one way or the other is quite distinctive. Once one learns it so one begins to see more and more of them while diving. At night they are easier to find because their eyes reflect light.
They will initially rely on their camouflage when approached by a diver. Provided that they do not feel threatened they will sit dead still. If they feel threatened they will open up their pectoral fins which are brightly colored in an attempt to warn the diver off. If that does not work they will hop away a few feet using their pectoral fins. Their poison is not as powerful as that of the Stonefish and is unlikely to kill a human. Instead one is likely to have extreme pain, nausea and the area affected will go white.
The treatment for a sting is imersion of the wound in hot water as hot as one can take it for about 90 minutes.
Devil Scorpionfish are found across the Indo Pacific area, all the way up the East coast of Africa from South Africa to the Red sea. They are usually found in out in the open on sand or rubble.
Devil Scorpionfish are ambush predators that prey on small fishes and crustaceans and pretty much anything that fits in their mouth. They use their proportionally large mouths to create a vacuum and suck in and swallow the prey. Prey is swallowed whole and is sucked into the mouth.
Devil Scorpionfish are oviparous with females producing eggs that when fertilized are released and float near the surface. Little else is known about their reproduction.
They are caught by some indigenous communities and the flesh is edible but as with any similar predator there is a risk of ciguatera poisoning.
Devil Scorpionfish are kept by some collectors in specialised aquariums, but they are not common in the trade. They will eat anything that fits into their rather large mouths so care has to be taken in this regard