Mullet (fish)

The mullets, or grey mullets, belong to a diverse family of ray-finned fish called Mugilidae.

These fish live in coastal temperate and tropical waters across the globe. Some specific species have also adapted to live in fresh water. The Mugilidae family is quite large, containing about 78 different species organized into 26 genera. Because they are such a widespread group, they play important roles in many different aquatic ecosystems. Scientists study them to understand how fish adapt to various environments.

Physically, mullets possess several unique characteristics that distinguish them from other fish. They have two separate dorsal fins located on their backs. Their mouths are notably small and triangular in shape.

One major difference is that they lack a lateral line organ, which is a sensory organ many other fish use. To process their food, mullets rely on specialized internal anatomy. They primarily feed on detritus, which is organic matter found in the water or on the seabed. To digest this, most species have developed unusually muscular stomachs and a complex pharynx, which is the part of the throat that leads to the esophagus.

Taxonomy, or the science of naming and classifying living things, places mullets in the order Mugiliformes. This order is named specifically after the fish themselves. While scientists once thought Mugiliformes contained only one group, recent research suggests a closer link to Asiatic glassfishes, known as Ambassidae. The presence of fin spines shows that mullets belong to the superorder Acanthopterygii. In the 1960s, researchers classified them as primitive perciforms. However, other scientific groupings have placed them within the order Atheriniformes. This ongoing classification work helps scientists map the complex tree of life.

There is often confusion regarding the name "mullet" depending on where you are in the world. In North America, the term usually refers directly to the Mugilidae family. In Europe, people use specific names to avoid confusion. They call the Mugilidae "grey mullets" and refer to the Mullidae family as "red mullets" or "surmullets."

Outside of Europe, members of the Mullidae family are commonly known as goatfish. Other fish, such as the freshwater Catostomus commersonii, also carry the name mullet but are not closely related. This highlights how common names can sometimes differ from scientific reality.

Mullets have a long and documented history of human interaction. They have been a vital food source in Mediterranean Europe since the Roman era. In ancient Egypt, people prepared them as a dried or pickled food called fesikh. Indigenous communities in North Carolina, Hawaii, and Florida have also fished for them since at least the 15th century. The fossil record also shows their long history. The oldest known fossil mullet is named Mugil princeps. This fossil was found in the Aix-en-Provence Formation in France and dates back to the latest Oligocene epoch.

One of the most striking behaviors of the mullet is its tendency to leap out of the water. Scientists observe two distinct types of jumps. The first is a straight, clean slice through the surface, which is likely used to escape from predators. The second is a slower, lower jump where the fish turns onto its side. This second movement creates a large, noticeable splash. While the exact reason for this jump is still debated, some hypothesize it helps the fish breathe. They may be seeking oxygen-rich air to assist a small organ located above the pharynx.

Modern science continues to investigate the development of these fish through ontogeny, the study of how an organism grows. The larvae of the species Mugil cephalus are studied very closely. This is because they are widely distributed and are important for aquaculture, which is the farming of aquatic organisms. A 2021 study investigated the osteological development, or the growth of the bones, in these fish. Researchers identified four embryonic steps and six larval developmental steps. This detailed work helps farmers recognize malformations in fish raised in controlled environments.