Dragonfish may refer to any of a number of different species of fish which have little in common aside from their name. These fish are largely unrelated to one another. Fish that are often called dragonfish include the deep sea dragonfish, the Asian arowana, the violet goby, and members of the Pterois genus, including the lionfish.
Those fish that are often called dragonfish are not native to the same geographic areas. It is not uncommon for the various species not to resemble each other in appearance. One commonality of all dragonfish species is their carnivorous eating habits.
The deep sea dragonfish, or black dragonfish, Grammatostomias flagellibarba, resides deep under the ocean, usually at a depth of 3,200 to 9,800 feet (1,000 to 3,000 meters) below the surface. It is a member of the Stomiidae family, whose members are often called barbeled dragonfish due to the photophore, a light-emitting organ attached beneath their jaw. The black dragonfish are slender and eel-like with large, over-sized teeth.
At the depth that this fish resides, there is little to no light penetration, which has caused them to develop bioluminescent properties. The black dragonfish possesses small light-emitting organs on the exterior of its body that draw prey to it. These organs also allow the fish to communicate with other members of its species. The fish is unique in its ability to produce red light in addition to a green-blue light. The eyes of most bioluminescent creatures that live at these depths have adapted to only perceive blue light, giving the black dragonfish a substantial advantage in communicating without alerting predators.
The Asian arowana is an endangered species of fish. It is a freshwater fish that mainly inhabits rivers, where it feeds on other fish. The body of this fish is medium to long, often reaching lengths of 35 inches (90 cm) and has very large scales that measure almost 1 inch long (about 2 cm). The Asian arowana is referred to as a dragonfish due to its resemblance to a Chinese dragon. It is often sought after as an aquarium fish, and in some cultures, the Asian arowana is believed to bring good luck.
Like black dragonfish, the violet goby is slender and eel-like in shape and can grow up to 2 feet (61 cm) in the wilderness. They have menacing-looking teeth and have developed a reputation for aggressive and territorial behavior. Goby act as scavengers, using their teeth to scrape algae off of debris.
Members of the genus Pterois, primarily the lionfish, are also called dragonfish. Pterois fish are venomous and have sharp spines that protrude from their bodies, which are used to fend off predators and play no role in hunting or capturing prey. Their coloring is often a striped red, white, and brown. They can be found in many tropic zones outside of their native Indo-Pacific region where their numbers are dangerously high.