Frogfish are a true joy to encounter underwater; these are one of the hardest fish to spot underwater, in fact most divers who encounter them will usually tell you it’s a real stroke of luck to bump into a frogfish on a dive. There are plenty of different species of frogfish for you to find, and they range in size from the tiny Randall’s frogfish which grows to 1.5 to 2 cm to the truly enormous by frogfish standards Ocellated frogfish which can reach 38 cm in length. The one thing that is constant—whether it is a 1.5 cm fish or a 38 cm frogfish—is that they are incredibly difficult to spot underwater! That is why they are considered by many macro hunters to be one of the top prizes to find underwater.
Frogfish have one of the most specialized and adapted bodies in the underwater world. Through evolution they have sacrificed body shape and hydrodynamics to become masters of camouflage. The frogfish can indeed exhibit a rainbow of colours, from black to yellow with all shades or orange, pink and brown in the middle, as well as body textures mimicking the bumps and patterns of substrates such as sponges, algae, seaweeds, rocks and encrusting corals. Besides being able to change colors to match their surroundings, they have also developed many extra appendages which hang off their body and make them more difficult to spot. When it comes to hunting, the frogfish has also evolved some neat tricks. Its forward dorsal fin has evolved from a fin into a fishing lure. The fin is now a long thin appendage that sticks out forward over the fish’s mouth. The end of the fin is fatter and rounder to mimic the shape of a juicy shrimp, attracting greedy predators within the grasp of the frogfish. Not only can the frogfish move its lure to make it resemble a shrimp, it can also completely retract it. As is often the case with lures, there is a strong possibility that the lure will get damaged or broken—well that is no problem for the frogfish since they can just regrow and regenerate the lure.
Frogfish lack a swim bladder, which means that unlike other fish which can control their buoyancy and swim through the water column, a frog fish would just sink if it tried to swim forwards. That is why frogfish prefer to walk around on the reef. They use their pectoral fins to walk or even sometimes gallop around on the sea floor. They have the ability to swim very short distances using their fins, but they are not very good at it and prefer to walk.
You would think being fluorescent goes against every rule of camouflage. But apparently not so for frogfish. Like many other marine creatures, several frogfish species can make their lure glow to attract prey especially in dark conditions. Recent research has found that not only the lures are fluorescent, but actually a big part of the frogfish’s body will fluoresce in certain lighting conditions. One of the best ways to experience this is to take part in a “Fluo night dive”, which uses a modified dive light and a special light filter for your mask. You will be amazed at how many fish boast this strange fluorescence. Up till now it is not clear why frogfish have this capability on their bodies.
Frogfish are tropical fish, they can be found in almost all tropical waters around the world. As a general rule, whenever you find a coral reef you will find some species of native frogfish. They are also considered like a prized species in some muck-diving, low visibility locations around the world. There is no specific species that completely circumnavigates the globe.