Learn more about this species - Eusphyra blochii

Winghead Shark
The Winghead Shark has its eyes set at the tips of its wide, T-shaped head. Scientists think that this positioning gives it a broader and more precise field of view. The Winghead is one of about ten species of hammerhead sharks.

Learn more about this species - Pristis pectinata

Smalltooth Sawfish
The long toothy rostrum or “saw” gives sawfish their common name. They use the saw to dig in the sand for crustaceans or to attack prey by vigorously slashing from side to side. Note that the radiograph is a composite: where the two images were spliced, the vertebral column appears to be “broken” behind the head.

Learn more about this species - Raja montereyensis

Monterey Skate
This species of skate or ray was named after the place it was first collected: Monterey Bay, California (U.S.A.). The specimen was collected in 1904 at a depth of about 50 meters (164 feet).

Learn more about this species - Latimeria chalumnae

Coelacanth
For many years, biologists thought that Coelacanths had gone extinct around the same time as the dinosaurs. Discovery of a living Coelacanth off the coast of South Africa in 1938 was one of the most dramatic scientific events of the 20th century. This specimen is a newborn. The National Collection of Fishes also has an adult Coelacanth that is 1.7 meters.

Learn more about this species - Atractosteus tropicus

Tropical Gar
Gars are voracious predators that use the teeth in their elongated jaws to trap other fish. Their tough body is covered with thick, bony scales, which are visible on the radiograph.

Learn more about this species - Enchelynassa canina

Viper Moray
Moray eels are legendary predators on coral reefs. Note the second set of jaws in the “throat”; these are the gill arches, which are present in all fish. Gill arches support the gills, the major respiratory organ of fish.

Learn more about this species - Nemichthys scolopaceus

Slender Snipe Eel
Snipe eels live at great depths in the ocean. This specimen was collected at over 2,000 meters (more than a mile down) in the North Atlantic. Snipe eels swim with their mouths open and feed on invertebrates. They have over 700 vertebrae, more than any other animal.

Learn more about this species - Eurypharynx pelecanoides

Pelican Eel
A deep-sea fish rarely seen by humans, the Pelican Eel has an enormous mouth with long, slender jaws (nearly horizontal in this image) that allow it to swallow extremely large prey. The fish inside this Pelican Eel’s stomach (poking out near the tail) was its last supper.

Learn more about this genus - Gastromyzon

Torrent Loach
The crescent-shaped paired fins on the underside of torrent loaches work like suction cups to help them hold their position on a rock or streambed in fast-flowing waters. These specimens belong to a newly discovered species that has not yet received a scientific name.

Learn more about this species - Mylossoma duriventre

Silver Mylossoma
This South American freshwater fish, a species of pacu, is a close relative of the piranhas and a popular aquarium fish.

Learn more about this species - Gasteropelecus maculatus

Spotted Hatchetfish
These freshwater hatchetfish have deep convex bodies with well-developed muscles that control their elongated pectoral fins. They can leap out of the water and glide for short distances.

Learn more about this species - Sternarchorhynchus retzeri

Retzer's Elephant-nose Knifefish
This species lives in deep waters of the Amazon Basin of South America and feeds on small invertebrates. Look for the black spot on the knifefish’s head in the color photo; this is an extremely small eye. Elephant-nose Knifefish don’t rely on sight. They find prey by electrolocation, producing and detecting weak electrical impulses.

Learn more about this species - Physopyxis lyra

Pirillo
Large, ornate pectoral spines extend from the sides of these small South American catfish. When locked in an open position, the spines prevent predators from swallowing the catfish.

Learn more about this species - Spatuloricaria atratoensis

a loricariid catfish
The “beard” on the head of this male South American catfish is made up of toothlike structures called dermal denticles and the body is covered in bony plates.

Learn more about this species - Oncorhynchus mykiss

Rainbow Trout and Steelhead
Rainbow Trout are important commercial food fishes, which are farmed as well as caught in the wild. Fish from some populations migrate to the ocean for part of their lives; these fish change in appearance and are known as Steelhead.

Learn more about this species - Argyropelecus lychnus

Tropical Hatchetfish
Marine hatchetfish (which are not closely related to the freshwater hatchetfish kept by aquarium hobbyists) live in the dark depths of the ocean; this specimen was collected at about 850 meters (2,789 feet) in the Pacific. As with many other deep-sea fishes, their eyes are large and their bellies have numerous small cream-colored spots (or “light organs”) that are bioluminescent. Each species emits its own unique pattern of light.

Learn more about this species - Lampris guttatus

Opah
Opah have a distinctive round, flat, silvery body and elongate red fins. These large, solitary marine fish are sometimes caught accidentally by commercial boats fishing for tuna.

Learn more about this species - Eumecichthys fiski

Unicorn Crestfish
Crestfishes’ ribbon-like bodies contain up to 200 vertebrae and have a soft-rayed dorsal fin with nearly 400 rays. The “horn” of the Unicorn Crestfish is formed by a protrusion of the skull, capped with a forward extension of the dorsal fin.

Learn more about this species - Ogcocephalus corniger

Longnose Batfish
Flat and wide, batfish look like they’ve been stepped on. They feed by skimming for prey along sandy bottoms. This Longnose Batfish had a taste for mollusks.

Learn more about this species - Halieutichthys aculeatus

Pancake Batfish
Thorn-like bony projections encircle the Pancake Batfish’s skull and follow the contours of its body near the tail. This flat-as-a-pancake fish is found on sandy ocean bottoms from North Carolina to Brazil.

Learn more about this species - Dermatias platynogaster

Bulbous Deep Sea Angler
Female anglerfish have a natural “fishing pole”—the long first spine of the dorsal fin is tipped with a bulb that may hold luminescent bacteria that attract prey. This anglerfish has a soft, fleshy body and, like many other deep-sea fish, spends its entire life in the water column, never touching bottom.

Learn more about this species - Cyttopsis rosea

Rosy Dory
The Rosy Dory has a large mouth that protrudes to pick small fish and invertebrates off the sea bottom in waters up to 700 meters (2296 feet) deep.

Learn more about this species - Oreosoma atlanticum

Ox-eyed Oreo
The name Oreosoma (“mountain body”) refers to the cone-shaped bony structures on the underside of this larval specimen. Adults are more elongate, less oval, and covered with scales.

Learn more about this species - Eurypegasus draconis

Short Dragonfish
The broad, expanded pectoral fins of this small marine fish recall the wings of mythical dragons. Despite their fierce appearance, dragonfish are harmless to humans and eat only crustaceans and insects.

Learn more about this species - Hippocampus sindonis

Dhiho's Seahorse
Just over one inch long, this elegant fish is readily identified as a seahorse by its characteristic head. The body ends in a tail that can curl around and hold on to algae or coral. This species is found only in the waters around Japan.

Learn more about this species - Syngnathoides biaculeatus

Alligator Pipefish
Pipefish may be thought of as seahorses unfurled. The numerous bony body rings are used to differentiate one species of pipefish from another.

Learn more about this species - Solenostomus cyanopterus

Ghost Pipefish
The Ghost Pipefish has a small mouth and elongate body like other pipefish and seahorses, but it differs in its delicate trailing fins.

Learn more about this species - Notopogon fernandezianus

Orange Bellowsfish
Between the bellowsfish’s skull and dorsal (back) fin is a fleshy tuft that is supported by many thin rods of bone. This species lives on continental shelves at depths of up to 580 meters (1,903 feet).

Learn more about this species - Centriscus scutatus

Grooved Razorfish
Razorfish, or shrimpfish, have a unique swimming style: they keep their bodies vertical (heads down, tails up) while propelling themselves forward in schools. Note that the back of the fish is bony and nearly straight; all of its fins are on its belly.

Learn more about this species - Scorpaenopsis obtusa

Shortsnout Scorpionfish
Scorpionfish have venomous glands in the spines of their fins, which can deliver a powerful, numbing toxin. This specimen was collected in the Philippines in 1908, but was not named as a new species until 2001.

Learn more about this species - Selene vomer

Lookdown
Because of its sloped head and the enlarged crest on its skull, the Lookdown appears to “look down” as it swims. These fish often swim in small schools.

Learn more about this species - Mene maculata

Moonfish
The Moonfish, found in the Indo-Pacific Ocean, has a distinctive, nearly round, flat body; a large mouth that protrudes for feeding; and a long, thread-like pelvic fin below.

Learn more about this species - Eugerres plumieri

Striped Mojarra
Silver-bodied mojarra school in warm, shallow coastal habitats. The thickened spines of its fins are boldly visible on this striped mojarra.

Learn more about this species - Forcipiger longirostris

Longnose Butterflyfish
Like butterflies, many butterflyfish have dramatic coloration, often yellow and black, and “eyespots” on their bodies. This specimen was collected in 2004 from French Polynesia and still retains much of its patterning, even though the alcohol that preserves the fish has caused its bright pigments to fade.

Learn more about this species - Plagiogrammus hopkinsii

Crisscross Prickleback
The radiograph reveals the fine details of this skeleton—especially the long, spiny dorsal fin that forms the prickles on the fish’s back. The quality of detail is remarkable, considering that this specimen from California was preserved a century ago, in 1910.

Learn more about this species - Evoxymetopon taeniatus

Channel Scabbardfish
Scabbardfish are elongate marine fishes with minuscule tail fins. This specimen comes from the Caribbean. Note the expanded, balloon-like bones at the base of the dorsal-fin rays, just above and behind the head. This unusual characteristic may be related to a high level of calcium in the water.

Learn more about this species - Morone saxatilis

Striped Bass
Native to marine and coastal habitats of eastern North America, this popular sport fish has been introduced broadly throughout the United States. This specimen was collected from the Sacramento River, California, in 2004.

Learn more about this genus - Chascanopsetta

A bothid flatfish
Adult flatfish swim on their sides and have two eyes on the same side of their head. During development, one eye migrates to the upward-facing side, leaving the other side blind.

Learn more about this species - Rhinecanthus rectangulus

Wedge-tail Triggerfish
Triggerfish discourage predators by erecting two sharp dorsal spines: a large, thick one and a shorter spine behind it. The second spine is the “trigger”; it locks the first one in place.

Learn more about this species - Diodon holocanthus

Long-spined Porcupinefish
To ward off predators, a porcupinefish inflates its body by pumping water into its stomach, transforming the fish into a round, rigid ball bristling with spines.