The eels is a group of elongated fishes ranging from small 5 cm to 4 metres. The majority being predators. Some species of similar shape (like electric and spiny eels) do not belong to the Anguilliformes order. There are about 800 described species in this order.
Aulopiformes is an order of marine ray-finned fishes sometimes called grinners or lizard fishes. The order is distinct by their common structure of their gill arches. There are about 15 described species of this order.
Beryciformes is an order of ray-finned fishes. There are no distinct characters for this order and some have questioned the relevance of the order. Most species are marine, living at great depths avoiding bright light. There are about 220 described species in this group.
Cetomimiformes (Whalefishes) is an order of small deep sea fishes. It is also the sister order of the Beryciformes. They are distinct in having very large mouths and highly distensible stomachs. Some species have been found to occur at depths more than 3.500 meters.
Clupeiformes is an order of fishes that typically lacks the lateral line. The species are often silvery and stream lined. Many have a tendency to form large groups. There are about 300 described species in this group.
Gadiformes is an order of ray-finned fishes that includes the cod and its allies. The majority of species are marine living all over the world, but, there also exists a few freshwater species. There are about 475 described species belonging to this order.
Gasterosteiformes (Sticklebacks and relatives)
Gasterosteiformes is an order of fishes that includes the sticklebacks and relatives. Instead of scales the body is covered with dermal plates. There are some confusion to the actual taxonomy related to this order. There are about 59 species belonging to this group.
Lampriformes is an order of deep sea fishes such as the crestfishes, oarfish, opahs and ribbonfishes. The scientific name refers to the body shape of the fishes, meaning "shaped like the bright ones". The species are pelagic feeders and are normally found between 100 - 1000 meters depth. There are about 50 living species of this order.
Lophiiformes or anglerfishes are an order of fish characterized by their special form of predation. From the fish head is a fleshy growth which acts as a lure to attract prey. There are described about 300 species belonging to this order.
Myctophiformes (Lanternfishes and Blackchins)
Myctophiformes is an order of ray-finned species consisting of two families: Myctophidae (lanternfishes) and Neoscopelidae (blackchins). The species often have large eyes and mouths. There are about 250 described species belonging to this order.
Notacanthiformes (Spiny eels)
Notacanthiformes is an order of deep sea ray-finned fishes, consisting of the families Halosauridae and Notacanthidae (spiny eels). The species are eel like and the caudal fin has disappeared from the species. The Notacanthiformes have a leptocephalous ("glass eel") larval stage. There are about 75 described species belonging to this order.
Osmeriformes is a broad order of fishes including the species of pike and salmon among many. The name “Osmeriformes” means “smelt-shaped” and, thus, refers to the body-shape of the fishes. There are about 90 described species belonging to this order.
The Perciformes (sometimes called the Percomorphi or Acanthopteri) is a large order of ray-finned fishes containing about 40% of all bony fishes. Perciformes refer to a perch-like appearance. The order is very various and contains both marine and freshwater species. There are about 7,000 described species belonging to this order.
Pleuronectiformes is an order of ray-finned fishes characterized by their flat shape. Pleuronectiformes also mean “side-swimmers”. Some species are able to almost disappear on the ocean floor with only their eyes being visible. There are about 400 described species belonging to this order.
Saccopharyngiformes (Swallowers and gulpers)
Saccopharyngiformes is an unusual order of fishes. The group mainly consists of deep sea species many with the ability to consume prey larger than themselves. There are about 400 described species belonging to this order.
Salmoniformes or the Salmons is a small group of fishes with large cultural and economic value. Many species of salmons have a life cycle involving both a feshwater and a saltwater stage. There are about 66 described species belonging to this group.
Scorpaeniformes (Mail-cheeked fishes)
Scorpaeniformes is an order of ray-finned fishes also known as the “mail-cheeked” fishes. The species are predators often living of small crustaceans and fishes. There are about 1320 described species belong to this group.
Stomiiformes (Stomias-shaped fishes)
Stomiiformes is an order of deep-sea ray-finned fishes and includes for example dragonfishes, lightfishes, loosejaws, marine hatchetfishes and viperfishes. Stomiiformes means “stomias-shaped”. The species can be found all over the world. There are about 400 described species belonging to this order.