This 4-inch slow moving reef fish is almost impossible to see but can cause a powerful venomous sting to a diver if you touch one. They have sail-like fins that are always erect and they sit motionless on the reef turning sideways to the surge from the surf above.
They look exactly like a leaf and they sway back and forth just like a leaf would do in the surge. They are ambush hunters and when I point them out to divers most people still don’t see them. The Leaf Scorpionfish are common in Hawai‘i but very rare in the rest of the tropical Pacific.
Nohu is the general name for all of our scorpionfish here in Hawai‘i and it is unclear if the ancient Hawaiians actually ever saw one! The unusual thing about the Leaf Scorpionfish is its variation in colors. This small fish can be brown, black, white, yellow, green or pink! It is fascinating to try and understand why you may find a pink one on one reef and a brown one on a different reef. Colors are important in the sea and there must be some benefit to being a different color on different parts of the reef.
I have divers often ask me how I can so easily find this fish because often when I do find one and point it out people just shake their head and say “I can’t see it”. Even when I point it out in a picture most people just think it is a rock or leaf until they look close.
All scorpionfish have a rounded pectoral fin. Out on the reef there are very few clean rounded rocks, corals or even leafs. I simply look for the shape of their fin, not their color. Once you get good at this you all of a sudden see these fish often when previously you may have gone right over them not knowing they are there.
While diving or snorkeling one should never touch the reef without wearing gloves as it is easy to put your hands right on top of a scorpionfish! These fish can give you a powerful injection of venom. They have grooves in their spines that act much like the teeth on a rattlesnake. Once they cut into your skin they squeeze a venom sack and inject the poison into your body which can be very painful and even cause you to go to the hospital.
The good thing is that nohu venom can be broken down with hot water so if you ever do get stung soak your limb in hot water which works quite well.
You can see nohu in action in my movie The Worlds Guide to Hawaiian Reef Fish on my web at www.underwater2web.com and also in my underwater documentary movies up on my YouTube at Underwater2web.
Terry Lilley is a marine biologist living in Hanalei Kaua‘i and co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawaii go to www.reefguardianshawaii.org.
Source: The Garden Island