The following article was the second in my ‘Species Crash Course’ series published in Asian Diver Magazine (issue 106) entitled ‘Species Crash Course: The Scorpionfish of Muck Dives’.

SPECIES CRASH COURSE: Identifying Scorpionfish on Muck Dives – By Richard Smith (© Richard Smith 2012)

Asian Diver Article - The Scorpionfish of Muck DivesThe Scorpionfishes of muck dive sites aren’t your run of the mill lionfish, they include some of the reef fish connoisseur’s most sought after treasures!

Scorpionfish are well represented on the muck dive sites of Asia such as Lembeh Strait, Komodo and Bali in Indonesia, Anilao in the Philippines and Milne Bay of Papua New Guinea.  Muck sites, for the uninitiated, sound like a pretty terrible place dive but these areas, often sandy and sheltered, are packed with unusual and unique creatures you won’t see on a coral reef.  You may come across tasselled scorpions and common lionfish but there are also Rhinopias scorpionfish, referred to as the “Photographer’s Holy Grail”, and a host of other oddities.

The Habitat –

muck diving has become really popular over the past ten to fifteen years and refers to sites which usually experience little current, primarily consist of a sandy bottom (often black sand) and depending on where you are there might be rubbish littering the ground.  The joy of muck diving is searching for the cryptic, hideous and downright bizarre creatures that make the area their home.  Many are so well camouflaged that only a beady eye gives them away.  Search for members of the scorpionfish family hiding in the sand (with only their eyes and mouth protruding), discreetly nestled amongst algae and even brazenly sitting out in the open, supremely confident of their camouflage.

The Science –

Scorpionfish belong to the family Scorpaenidae, which contains the lionfishes, Rhinopias and leaf scorpions as well as the more typical reef scorpionfishes.  Closely related, but belonging to the family, Synanceiidae, are the stonefishes and demon stingers.  All scorpionfishes possess spines containing neurotoxic venom that is produced by paired glands at their base.  Great care should obviously be taken not to touch the fish but if accidentally pierced by the spine the best treatment is to immerse the wound in as hot water as possible, which will eventually break down the venom, rendering it inactive.

Scorpionfish are ambush predators, relying heavily on their camouflage for a hapless fish to stray too close to the gaping mouth.  You may notice that the mouths of many scorpionfish are relatively large.  The fish is able to open it very quickly and almost suck the prey into the mouth and subsequently swallow it whole.  Many species are not at all well adapted for swimming and have gone so far as loosing their swim bladder, which is vitally in buoyancy control for most fishes.  As a result swimming is quite a great effort.  Finding a mate can also be slightly troublesome so some remain in mated pairs and do not stray far from their partner, although the majority are solitary.


The Species –

Short fin lionfish (Dendrochirus brachypterus)Short-Fin Lionfish – (Dendrochirus brachypterus):  Finding the short-fin lionfish is a great indication that you are in the right habitat for many of the other species.  Where conditions suit them they can be abundant and these same conditions will also suit some of the rarer species.  Hint: time to keep your eyes peeled!  The short-fin is also known as the dwarf lionfish and is found in a variety of colour forms including a rare yellow form.  Unlike some of the other species included here it is quite an active species that can often be seen patrolling small rock bommies or sandy areas for a snack.

Weedy Scorpionfish (Rhinopias frondosa)Weedy Scorpionfish – (Rhinopias frondosa):  There are two species of scorpionfishes in the genus Rhinopias that can be found on muck dives.  The weedy must not be confused with the lacy scorpionfish (Rhinopias aphanes), which is only found in the Coral Sea area bordered by Papua New Guinea, Australia and the Solomon Islands.  The lacy is exclusively found on rich coral
reefs and not muck sites that are the domain of the weedy and paddle flap species.  The colour of weedy scorpionfish varies greatly and depends directly on the type of algae or substrate around the animal.  In photographs they seem gaudy and you might think they would stick out like a sore thumb but they definitely earn the accolade of the “photographer’s Holy Grail” requiring a great deal of patience and luck to find!

Paddle flap scorpionfish (Rhinopias eschmeyeri)Paddle Flap Scorpionfish – (Rhinopias eschmeyeri):  Another species of Rhinopias that with a great deal of luck be found on muck dives.  Like other Rhinopias it reaches a maximum size of 20-25 cm and is also found in many colours although most commonly pink, red or off white.  It can be identified by the lack of tassels and weedy appendages over the body, a uniform colouration and the smooth, paddile-like, edges to the fins.  Rhinopias are most often found at over 20 meters depth and will happily sit in the open, whilst matching their habitat perfectly.  They prefer rubble slopes rich in algal, sponge and soft coral growth.  Some of the best locations to see them are Lembeh Strait, Ambon and Komodo in Indonesia as well as Anilao in the Philippines.

Leaf scoprionfish (Taenianopterus triacanthus)Leaf Scorpionfish – (Taenianotus triacanthus):  The leaf scorpionfish is a jack of all trades and is equally happy hanging out on a reef wall or on a muck site amongst a pile of leaves!  These ranges in habitat preference mean there is a corresponding variety of colour forms of this species.  The most striking perhaps is a bright pink but on muck dives the more subdued white, yellow and brown forms are more common.  If disturbed the animal will begin to sway from side to side in an attempt to convince you that it is in fact a leaf that you are looking at!

Ambon scorpionfish (Pteroidichthys amboinensis)Ambon Scorpionfish – (Pteroidichthys amboinensis):  This is surely one of the most comical members of the group.  The huge cirri (skin flaps) above the eyes, which have given it the alternate name of Bugs Bunny scorpionfish, are the diagnostic feature of this species.  It is usually found crawling around in an open sandy area with sparse patches of algae.  They are virtually always found in pairs with the larger individual the female and the small one the male.  Like many of the muck site scorpions the Ambon varies in colouration depending on the predominant colours at the specific locality.  I have seen yellow, brown, maroon and pink individuals.

Gurnard Lionfish (Parapterois heterura)Gurnard Lionfish – (Parapterois heterura):  Like its namesake, the flying gurnard, the gurnard lionfish is quite a drab well-camouflaged fish until startled.  Suddenly, it will spread open its large pectoral fins revealing the bright blue and black streaked inner surface of the fin.  This is actually a very rare fish and is only found in several localities with quite specific habitat characteristics.  It prefers sandy slopes, where it will often remain partially buried in relatively shallow water at the edge of where the slope drops off steeply.  They usually occur in pairs so if you see one then scan the area for its mate.

Demon Stinger (Inimicus didactylus)Demon Stinger – (Inimicus didactylus):  Also referred to by the genus name Inimicus this group, containing several species, can be distinguished by the patterns displayed on the inner surface of the pectoral fins.  They are often seen crawling along the bottom using little ‘fingers’.  These are in fact the lowest 2 or 3 rays of the pectoral fins that are thickened and used to drag the animal around or search for prey in the sand.  They often remain half buried with only the head and sharp spines protruding.  Depending of the habitat in which you find them, the colouration can range from pale to very dark and a site in Lembeh Strait is even known for an orange/red morph.

The Photography – Scorpionfish are a pretty robust bunch and don’t appear to mind having their photograph taken.  Indeed some species seem so convinced of their camouflage that they will remain motionless for an entire photo shoot.  Having said that they are wild animals and probably value their retinas for feeding so try not to take too many shots with huge powerful lights!  For the more skittish species a careful, slow approach will get the best results and always be careful not to damage any marine life when taking your pictures.  The most preferable method in a muck dive situation is to hover neutrally above the sand.  This probably isn’t the easiest way but it will stop you from stirring up the fine sediment and from being silted out.