The 11 Weirdest Fish

Fish are some of the weirdest vertebrates on earth—and some fish are definitely more bizarre than others. In the following images, you'll discover 11 of the strangest fish in the world's oceans, ranging from the laughter-provoking blobfish to the nightmare-inducing stargazer.

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The Blobfish

Blobfish at their appropriate sea depth.

Rachel Caauwe / Wikimedia Commons / CC-BY-SA-3.0

Pity the poor blobfish. In its natural habitat, at ocean depths of between 3,000 and 4,000 feet, it looks like a perfectly ordinary fish. When it's hauled up to the surface, however, its body expands into a comical-looking blob of big-nosed goo—with a face that looks remarkably like a human face.

The gelatinous flesh of Psychosrutes marcidus evolved to withstand extreme deep-sea pressure, while at the same time allowing this fish to float atop the seafloor, ingesting organic matter. Removed from its natural high-pressure environment, the blobfish swells up into the stuff of nightmares. (Blink and you missed it, but the blobfish appeared in the Chinese-restaurant scene in "Men in Black III"; most people assumed it was a special effect rather than a real animal!)

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The Asian Sheepshead Wrasse

Asian sheepshead wrasse
DigiPub / Getty Images

The name "wrasse" derives from the Cornish word for "hag" or "old woman." It's an apropos name for the Asian sheephead wrasse, Semicossyphus reticulatus, whose face looks like the cartoonishly exaggerated face of a classic Disney witch, including a protruding chin and forehead. Not a whole lot is known about the Asian sheepshead, but most likely this fish's oversized face is a sexually selected characteristic: Males (or perhaps females) with bigger, knobbier mugs are more attractive to the opposite sex during mating season. One piece of evidence in favor of this hypothesis is that newly hatched Asian sheepshead wrasses have ordinary heads.

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The Yellow Boxfish

Yellow boxfish juvenile
MichaelStubblefield / Getty Images

The marine equivalent of those rectangular watermelons they sell in Japan, the yellow boxfish frequents the coral reefs of the Indian and Pacific oceans, feeding on algae and small invertebrates. No one is quite sure why Ostracion cubicus bucked the usual piscine evolutionary trend toward flat, narrow bodies, but its agility in the water seems to owe more to its fins than to its overall shape. Here's a bit of pop-culture trivia for you: In 2006, Mercedes-Benz unveiled the Bionic, a "concept car" modeled after the yellow boxfish. If you've never heard of the Bionic, that's probably because this car was a true evolutionary flop compared to its more successful inspiration.

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The Psychedelic Frogfish

Psychadelic Frogfish

Rodger Klein / Getty Images

Frogfish, in general, are some of the strangest creatures on earth: They lack scales, sport various appendages and growths on their bodies, and are often covered with algae. But no frogfish is stranger than the psychedelic frogfish. Only discovered in 2009 in the waters of Indonesia, Histiophrine psychedelica has a large, flat face, beady blue eyes, a giant mouth, and, most tellingly, a striped white-orange-tan pattern that presumably allows it to blend in with surrounding corals. For any potential prey that isn't suitably mesmerized, the psychedelic frogfish also sports a tiny "luring appendage" on its forehead that vaguely resembles a wriggling worm.

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The Moonfish

GuidoMontaldo / Getty Images

In terms of its appearance, the moonfish is nothing special—you might overlook it if you saw it in an aquarium. Indeed, it's pretty ordinary next to some of the other fish in this list. What makes the moonfish truly unusual isn't its exterior, but its interior: This is the first identified warm-blooded fish, meaning it can generate its own internal body heat and maintain itself at a toasty 10 degrees Fahrenheit above the temperature of the surrounding water. This unique physiology endows the moonfish with more energy (it has been known to migrate for thousands of miles) and also allows it to sustain itself in its challenging deep-sea environment. The compelling question is: If endothermy is such a positive adaptation, why haven't other fish evolved it as well?

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The Goblin Shark

Goblin shark

Dianne Bray / Museum Victoria / Wikimedia Commons / CC-BY-3.0

The deep-sea equivalent of Ridley Scott's Alien, the goblin shark is characterized by its long, narrow upper snout (on the top of its head) and its sharp, protrusible teeth (on the bottom). When within range of its prey, Mitsukurina owstoni forcibly ejects its snapping lower jaws and reels its catch in. (Don't be too frightened, though; the goblin shark is unusually lazy and sluggish, and probably couldn't overtake a suitably adrenalized human being.) M. owstoni seems to be the only living representative of a family of sharks that prospered during the early Cretaceous period, 125 million years ago, which goes a long way toward explaining its unique appearance and feeding style.

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The Atlantic Wolffish

Atlantic wolffish
Jezperklauzen / Getty Images

The Atlantic wolffish, Anarhicas lupus, makes this list for two reasons. First, this fish is equipped with a pair of uncannily wolf-like jaws, with sharp incisors in front and shredding teeth in back suitable to its diet of hard-shelled mollusks and crustaceans. Second, and even more strikingly, A. lupus inhabits such frigid Atlantic waters that it manufactures its own "antifreeze proteins," which prevent its blood from congealing in temperatures as low as 30 degrees Fahrenheit. Although this uncommon chemical component makes the Atlantic wolffish undesirable as a food fish, A. lupus is caught up in deep-sea trawling nets so often that it is on the brink of being endangered.

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The Red-Bellied Pacu

Red-bellied Pacu portrait
Paolo_Toffanin / Getty Images

The red-bellied pacu looks like it has been summoned from a nightmare, or, at the very least, a David Cronenberg movie. This South American fish has uncannily human-like teeth: The resemblance is so close that pacus make headlines whenever they're caught outside their usual habitat. As weird as they are, red-bellied pacus are marketed as "vegetarian piranhas" by some pet stores, the owners of which often neglect to tell their customers two important facts. Pacus can inflict serious crushing bites on the fingers of unwary toddlers, and a three-inch-long juvenile pacu can quickly exceed the dimensions of its fish tank, requiring larger and more expensive accommodations.

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The Ocellated Icefish

The Ocellated Icefish

DeWitt & Hureau, 1979 / / Public Domain

Pretty much every vertebrate animal on earth uses the protein hemoglobin (or some variant thereof) to carry oxygen, which gives blood its characteristic red color. Not so the ocellated icefish, Chionodraco rastrospinosus. It's clear, water-like blood is completely hemoglobin-free: This Antarctic fish makes do with whatever oxygen dissolves into its blood straight from its oversized gills. The advantage of this arrangement is that the blood of C. rastrospinosus is less viscous and more easily pumped throughout its body. The disadvantage is that the ocellated icefish has to settle for a relatively low-energy lifestyle because extended bursts of activity would quickly deplete its oxygen reserves.

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The Toothpick Fish

Toothpick fish

Francis de Laporte de Castelnau / Wikimedia Commons / Public Domain 

One of the world's few identified parasitic fish, the toothpick fish, Vandellia cirrhosa, spends practically its entire life nestled in the gills of the larger catfish of the Amazon River. That's unusual enough in itself, but what merits V. cirrhosa's inclusion on this list is the popular belief that it has an unhealthy attraction to the human urethra, and will painfully parasitize anyone foolish enough to venture into the water. There is only one well-attested account of this actually happening—to a 23-year-old male in 1997. But. even in this case, the testimony of the victim doesn't quite match up to the forensic evidence. As one investigating doctor later said, the odds of winding up with a toothpick fish lodged in your urethra are about the same as "being struck by lightning while simultaneously being eaten by a shark."

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The Stargazer

Marbled Stargazer (Uranoscopus bicinctus)
RibeirodosSantos / Getty Images

Described by one naturalist as "the meanest thing in creation," the stargazer fish is equipped with two big, bulging eyes and one enormous mouth on the top, rather than the front, of its head; this fish buries itself on the ocean bottom, from whence it pounces on unsuspecting prey. Repulsed yet? Well, that's not all: Stargazers also grow two venomous spines above their back fins, and some species can even deliver mild electric shocks. Despite all this menacing weaponry, the stargazer is considered a delicacy in some countries. If you don't mind your dinner staring back at you from your plate, and you're confident the chef has successfully removed its toxic organs, feel free to order one if you find in on a menu.

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Strauss, Bob. "The 11 Weirdest Fish." ThoughtCo, Sep. 1, 2021, Strauss, Bob. (2021, September 1). The 11 Weirdest Fish. Retrieved from Strauss, Bob. "The 11 Weirdest Fish." ThoughtCo. (accessed June 1, 2023).