Everyone knows what a fish is: from a pet goldfish to a wild sunfish, fish are globally recognized and are an important global protein source. In this slideshow, we will look at some of the most interesting and amazing species of fish that live in the ocean. Which fish gets its name from the 1950’s horror movie The Blob? Which fish has a special protein that prevents its blood from freezing as is swims through the Arctic waters? And which fish has a separate set of jaws that grab prey from its mouth and pulls it down its throat? Find out in this slideshow!


Sweetlips, Raja Ampat, Indonesia
Credit: Jose Alejandro AlvarezThe larger fish in this picture are called sweetlips (Plectorhinchus) because of their big, fleshy lips. There are over thirty species of sweetlips, which tend to live on coral reefs in small groups.
“On an afternoon dive, I spotted a small group of sweetlips in the current among a shoal of juvenile convict blennies. It took me some time to get close to the fish without spooking them. I took several frames but this one was my favorite because of the position of the fish, particularly the one on the right who seems to be yawning.” -- Nature's Best Photographer, Jose Alejandro Alvarez

Striped Eel Catfish
Credit:Mauritius100, Flickr
When most people think of catfish, they think of a freshwater fish. But the striped eel catfish (Plotosus lineatus) is found in marine systems including coral reefs, estuaries, tide pools and other coastal areas of the Indo-Western Pacific. The juveniles of the fish school in groups of up to 100, while the adults tend to stick to themselves or in smaller groups. Watch out for their spines: they contain a dangerous venom that can even prove fatal to humans in rare cases!

Frogfish Histrio histrio
Credit: Seabird McKeonThe Sargassum frogfish Histrio histrio (Antennariidae) is a small but voracious predator - it can ingest animals up to it’s own size! The fins of the frogfish are perfect for creeping around in the algae and stalking unsuspecting prey.
Off the coast of Belize, Smithsonian Marine Science Network postdoctoral fellow, Seabird McKeon, studies floating seaweeds and the minuscule animals that call them home. Check out his slide show and blog and be amazed by the vast array of tiny life forms floating in the world adrift.

Yellow Goby
Credit: © Brian Skerry, www.brianskerry.comA tiny yellow goby, Lubricogobius exiguus, living inside an abandoned can on the seafloor; Suruga Bay, Japan

Blob Sculpin
Credit: NOAA, Alaska Fisheries Science CenterThe ghoulish “blob sculpin” (Psychrolutes phrictus), a deepwater fish found off the Pacific coast of the U.S. from the Bering Sea to Southern California, can grow to about 70 cm (more than two feet) in length and eats small invertebrates. See more bizarre-looking ocean life in a slideshow of the scariest monsters of the deep-sea and learn more about the deep ocean in the Deep Ocean Exploration section.

Arctic Cod Under Ice
Credit: E. Siddon, UAF, Hidden Ocean 2005, NOAA.Arctic cod have a special protein that keeps their blood from freezing in ice-cold Arctic waters.

A School of Hawaiian Squirrelfish
Credit: James Watt, USFWS PacificCheck out the eyes on these Hawaiian squirrelfish (Sargocentron xantherythrum)! Because squirrelfish are almost entirely nocturnal, they need big eyes to absorb as much moonlight and starlight as they can in the dark. During the day, they hide out in the nooks and crannies of tropical coral reefs. To defend its small hiding place, the squirrelfish grunts by grinding its teeth and stretching the muscles along its gas bladders—grunts that sound a bit like the chatter of squirrels!

Hiding Blennie
Credit: Chuck SavallPortrait of a yellow-green blennie (family Clinidae) hiding in the groove of a green brain coral.

A Baby Moray Eel, or a Really Small Adult?
Credit: Trish Mace, Smithsonian InstitutionThis is an unidentified moray eel, collected from 650 feet off the coast of Curacao. Morays are very secretive animals that tend to stay hidden in caves and crevices. Researchers with the Deep Reef Observation Project (DROP) don't yet know if this is a young eel, or a small full-grown one. By analyzing this moray's DNA and comparing it to DNA from known morays in the Caribbean, they will determine if this small eel is a juvenile of a known species.

Candy Basslet
Credit: Ross RobertsonA candy basslet (Liopropoma carmabi ) was one of the specimens Smithsonian scientists collected from the deep reefs of Curaçao on a 2011 research trip in the southern Caribbean. Learn more about the scientists' research on the Summer in Sub Blog

Seagrass and Shoal of Fish
Credit: Richard Unsworth/Marine PhotobankHardy head silversides (Atherinomorus lacunosus) are abundant fish in shallow water seagrass meadows throughout the Indo-Pacific that often form shoals. They feed primarily on zooplankton and small benthic invertebrates, and are an important part of the seagrass food web because they make an excellent food source for larger fish species.

Butterflyfish and Wrasse
Credit: © Brian Skerry, www.brianskerry.comA wrought iron butterflyfish, Chaetodon daedalma, being cleaned by a small wrasse in the waters of Japan's Ogasawara Islands.

Bigeye Jacks and Diver Balicasag, Philippines
Credit: Steve De Neef, Antwerp, Belgium www.stevedeneef.com"I was photographing this beautiful school of jacks when a diver slowly approached from beneath. I shifted my position to capture the moment he entered the ball of fish. Seconds later, he was completely immersed in the school.” -- Nature's Best photographer, Steve De Neef
See a slideshow of other photos from the 2011 Nature's Best Photography Ocean Views Contest.

Bait Ball
Credit: Flickr User CritidocThis bait ball shows how small fish can react when larger predators are near by gathering tightly together in a ball-like formation that exposes the least number of fish. Fish species found in the open ocean are especially in need of some protection, as they don't have the cracks and crevices that fish in coastal or coral reef habitats have to hide away. Instead, they hide behind one another to form a spherical bait ball, a shape which allows for the protection of the most fish. In some cases, however, predators have adapted in order to get their food despite the movement of their small prey.

Lanternfish
Credit: E. Widder, ORCA, www.teamorca.orgThis lanternfish (Diaphus sp.), found in the Red Sea, has light-producing photophores along its ventral surface (belly), and a nasal light organ that acts like a headlight. Hear scientists tell stories about encountering bioluminescent marine animals in the deep sea.

Yellowfin Surgeonfish
Credit: © Brian Skerry, www.brianskerry.comA school of yellowfin surgeonfish, Acanthurus xanthopterus, feed near dusk off Canton Island in the Phoenix Islands, one of the world's largest marine protected areas.

Pinecone Fish
Credit: Spencer WrightThe pinecone fish (Monocentris japonicus) looks like the real thing on land—covered in large scales with a dark trim. They are found lurking in caves and under ledges in the Indian and Western Pacific Oceans, and are a popular aquarium fish.

Gobies on Coral, Near Marsa Alam, Egypt
Credit: Tobias Friedrich/Nature's Best PhotographyGobies make up the largest family (Gobiidae) of fishes in the world, with over 2,000 species. In this large family you can also find the smallest fish. The gobies in this photo are about one inch long (2.5 cm), and most in the family are less than four inches. Because of their small size gobies must work to evade their many predators, often through burrowing or special mutualistic relationships with other animals.
“It’s quite normal for this type of goby to sit still on hard coral like this. I spotted the first of these very small fish and set up my camera for the shot. Just as I was about to take a picture, a second goby came out of nowhere and sat on the first one. I quickly corrected the frame and took two or three shots before both of them disappeared. It was an incredible moment.”-- Nature's Best Photographer, Tobias Friedrich

Dragonfish from Australia
Credit: Dr. Julian Finn, Museum VictoriaDeep-sea species like this dragonfish (Bathophilus indicus) live in cold, dark waters and may go weeks or months between meals. When food is found, the fish uses its impressive teeth—including some on its tongue—to get a tight grip on its prey.

Spotfin Lionfish
Credit: Chuck SavallThe spotfin lionfish (Pterois antennata), with venomous spines extended, is native to Indo-Pacific reefs. Certain lionfish species have invaded reefs in Florida, the Caribbean and are moving up the Atlantic coast. The native Pacific fish probably escaped from an aquarium. Lionfish are aggressive predators and threaten local species. They are also referred to as turkeyfish because depending on how you view the lionfish it can look like the plumage of a turkey. See more bizarre and beautiful coral reef animals.

Parrotfish in Mucus Cocoon
Credit: Lexa GrutterA parrotfish (Chlorurus sordidus) creates a mucus cocoon to protect it from parasites, like bloodsucking isopods, while it sleeps. Read more from the Citizens at Sea blog.

Snowflake Moray Eel
Credit: Flickr User Michael BentleyNo two snowflakes are alike. Every snowflake is beautiful in its own way. But this one’s a bit scary. The snowflake moray eel (Echidna nebulosa) has white, black and yellow splotches all over its body, which come together to look like snowflake designs. Moray eels eat their prey in a unique way – with two jaws. The second set of jaws is in their throat, which shoots up and grabs the prey from the main pair of jaws, drawing the prey down to the esophagus.

Parasitic Worms in a Fish
Credit: Hans HillewaertThe whitish spots on this fish are individual parasitic trematode worms. Trematodes have complicated life cycles that usually involve multiple hosts -- often starting in a snail and then moving on to other hosts, such as fish, birds, and mammals (including humans). They may have even lived in dinosaurs! Read more about parasites in marine organisms.

Flounder Faces Pollution and Overfishing in Baltic Sea
Credit: © OCEANA Carlos MinguellFor centuries, the Baltic Sea has provided European flounder (Platichthys flesus) and other fish for millions of people to consume. Since the early 1980s, the nations surrounding the sea have coordinated their efforts to protect its health through the Helsinki Commission. In addition to being overfished, the Baltic Sea is one of the more polluted bodies of water in the world. You can read about some of the impacts that chemical pollutants have had on European flounder on the IUCN's Red List of Threatened Species website. View other images of Baltic Sea life in a photo gallery of Oceana’s 2011 expedition.

Sockeye Salmon, Adams River, British Columbia, Canada
Credit: Todd Mintz, Regina Saskatchewan, Canada, www.tmintz.com“Every four years, sockeyes come inland from the Pacific to spawn. The year 2010 was the largest run in 100 years, reaching more than 30 million fish. On this day, I waited for the right sunlight, then quietly slipped into the river. Fighting the rush of the current, I positioned myself in front of the fish as they hugged the shore." -- Nature's Best photographer, Todd Mintz
See a slideshow of other photos from the 2011 Nature's Best Photography Ocean Views Contest.

Cardinalfish Dad with a Mouthful of Eggs
Credit: Flickr user Klaus Stiefel (PacificKlaus)Cardinalfish (Cheilodipterus sp.) dads do their part to protect their eggs by gingerly carrying them in their mouths. However, the dads could easily swallow the whole bunch in one gulp! To keep her eggs alive, the cardinalfish mom will often lay a number of yolkless dummy eggs along with the real ones. These dummy eggs trick the dad into thinking he has more future offspring in his mouth -- and thus the clutch is worth careful protection.

Weedy Seadragon, Flinders pier, Flinders, Victoria, Australia
Credit: Richard Wylie/Nature's Best PhotographyWeedy seadragons (Phyllopteryx taeniolatus) are found off the coast of south and east Australia. Just like seahorses, the male seadragon is tasked with caring for its eggs. The bright pink eggs are placed by the female on a brood patch on the underside of the male where they are incubated and then hatch after about six weeks.
“The male weedy seadragon is entrusted with the pink, fertilized eggs once mating has been completed. It is his task to incubate them until their hatching, approximately eight weeks later. The day this photo was taken, the weather and conditions were unusually perfect: blue skies, little to no wind, and clear water. I took this photo while on my back under the local sea plants, looking up as it swam by.” -- Nature's Best Photographer, Richard Wylie

X-Ray Image of Grooved Razorfish
Credit: Sandra J. Raredon / Smithsonian InstitutionAn X-ray image of grooved razorfish (Centriscus scutatus). Razorfish are encased in thin, transparent bony plates attached to their spines, which you can see in the X-ray. Also known as shrimpfish, razorfish 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.
Scientists in the Division of Fishes at the Smithsonian's National Museum of Natural History use X-ray images, like the one shown, to study the complex bone structure and diversity of fish without having to dissect or damage the specimen. In 2012, the National Museum of Natural History hosted "X-Ray Vision: Fish Inside Out," a temporary exhibit that showcases fish evolution and diversity through 40 black and white X-ray images prepared for research purposes. See more photos from the exhibit.

A New Fish DROP-ping In
Credit: D. Ross Robertson and Carole C. BaldwinBy diving in the Curasub, Smithsonian researchers with the Deep Reef Observation Project (DROP) have discovered a new species of tiny fish in the biodiversity-rich waters of the southern Caribbean. The fish, a blenny named Haptoclinus dropi, is only around 2 cm in length with a beautiful color pattern that includes iridescence on the fins. Against a white background, it's hard to see the beautiful coloration; but against a dark background, such as that found in deep water, the colors and iridescence stand out easily. Read about more discoveries from the DROP team on the Summer in a Sub blog.

Toothy Goby in Coral
Credit: Mark Rosenstein, FlickrThe toothy goby or common ghost goby (Pleurosicya mossambica) lives among soft corals and sponges in the Indo-Pacific ocean. The relationship it has with its host is commensal, which means the goby benefits from the protection and habitat in the corals, but the coral doesn't get hurt or benefit from the relationship.
Many of the other 2000 or so species of gobies form such symbiotic relationships, both commensalisms and mutualisms. Gobies and pistol shrimps will live together, with the near-blind shrimp tending their sandy burrow while the goby watches for predators. And cleaner gobies (Elacatinus) clean the mouths of bigger fish that would normally treat them as prey.