1. Some Fish Fart to Communicate
Turns out fish talk isn’t just about bubbles. It is bubbles. Herring communicate by releasing bursts of air from their rear ends in a pattern scientists call “fast repetitive ticks” (FRTs). This weird little system helps them coordinate movements in the dark. It’s not random. It’s intentional and sometimes sounds like rapid clicks to divers. Marine biologist Ben Wilson once joked, “It’s like a secret fish code.” So yes, some fish basically hold underwater group chats with their butts. Who knew fish had better communication skills than some people at dinner parties?
2. The Barreleye Fish Has a Transparent Skull
At first glance, the barreleye fish looks like something from a sci-fi film. This deep-sea dweller has a see-through head dome that reveals bright green eyes inside. It sounds fake, but it’s completely real. The eyes point upward to detect faint silhouettes of prey above but can also swivel forward when feeding. Think of it like built-in underwater binoculars. In the deep ocean where sunlight barely reaches, this strange feature gives the barreleye a survival edge. It’s like wearing goggles inside your own skull. Creepy, clever and completely mesmerizing to scientists who study it.
3. Parrotfish Poop Becomes Tropical Sand
White sand beaches might not feel the same after you hear this. Much of that soft sand is actually parrotfish poop. These colorful reef fish munch on coral to eat the algae living inside. The coral they can’t digest gets ground up and passed out as fine, sandy waste, \up to 200 pounds a year per fish. Marine ecologist Dr. Gareth Williams calls them “unsung sandmakers.” So the next time you build a beach castle, remember you’re playing with recycled coral. Somehow, nature even turns digestion into paradise. Literally beneath your toes.
4. Climbing Gobies Scale Waterfalls with Their Mouths
While most fish swim, the Hawaiian Nopili goby climbs. Seriously. This tiny freshwater fish uses its specially adapted mouth like a suction cup. It clings to wet rock faces and slowly pulls itself up waterfalls. Scientists have tracked them scaling up to 300 feet. It’s a slow crawl, not a leap, but it gets them to breeding spots upstream. “They’re some of the most determined fish on the planet,” says aquatic researcher Ashley Robart. It’s a quiet show of strength from a creature barely three inches long. Who says you need legs to reach new heights?
5. Lungfish Can Survive for Years Without Water
The African lungfish doesn’t panic when its pond dries up. It just waits. When water disappears during drought, it burrows into the mud and creates a protective cocoon. Inside, it breathes air using its primitive lungs and enters a state called estivation. Some have survived like this for over three years. It’s nature’s version of hitting pause. Evolutionary biologist John Gorman calls it “one of the most extreme adaptations on Earth.” While we rely on air conditioning, this fish basically naps through the worst weather. Sometimes doing nothing is the smartest move.
6. Stonefish Are Deadlier Than Sharks
Camouflaged like a lump of coral, the stonefish is the kind of ocean creature you don’t want to step on. Its spiny dorsal fins carry venom strong enough to kill a human in under an hour. Victims experience intense pain, swelling and even heart failure if not treated fast. Marine toxicologist Jamie Seymour says, “It’s the most venomous fish we know.” The danger lies in how invisible they are, often mistaken for rocks. Sharks may be scary, but this bottom-dweller is the real silent killer of the reef. Nature has a dark side and it blends in.
7. Clownfish Can Swap Gender
You’ve probably heard of clownfish thanks to Nemo, but the real twist is that clownfish can change sex. All are born male. If the dominant female dies, the strongest male transforms into a female and takes her role. It’s a permanent and natural change that helps maintain their small group structure. Marine biologist Deborah Gabriele explains, “It’s not random, it’s hierarchy-driven.” Unlike in most species, reproduction here is a team effort where everyone plays a role, even if that means changing who they are. It’s biology’s way of saying go with the flow.
8. Flying Fish Can Soar 20 Feet Above Water
Some fish don’t just swim. They glide through the air like tiny jets. Flying fish leap out of the water, spread their wing-like pectoral fins and use updrafts to soar as far as 20 feet (6 meters). Some have been recorded staying airborne for over 40 seconds. This escape strategy helps them dodge predators like tuna and marlin. Sailors have long mistaken them for birds skimming waves. “It’s like evolution tried aviation,” one researcher joked. If you’ve ever wanted proof that life adapts creatively, these airborne swimmers are fishy proof that survival takes flight.
9. The Devil’s Hole Pupfish Lives in One Desert Cave
In the middle of Nevada’s desert lies a tiny water-filled cavern called Devil’s Hole. It’s home to just one species, the Devil’s Hole pupfish. Fewer than 200 live here at any time and it’s one of the rarest vertebrates on Earth. These tiny blue fish have survived in this 93-degree water for thousands of years. Conservationists monitor them closely because of their fragile habitat. “It’s a symbol of how isolated life can be,” says biologist Katie Glover. It’s living proof that even in the loneliest corners of the world, life can still flourish.
10. Four-Eyed Fish Actually See Above and Below Water at Once
If you’ve ever wished you could multitask with your eyes, meet the four-eyed fish. Found in Central and South America, this surface-dwelling species has horizontally split eyes. One half is adapted to see above water and the other below. It allows them to spot birds overhead while also tracking insects and predators beneath. It’s the ultimate two-in-one deal and no glasses required. “They live in two worlds at once,” notes ichthyologist Daniel Rosa. It’s an eye-opening trick from nature’s playbook, showing us how vision can stretch far beyond the limits we’re used to.
11. Icefish Have Clear Blood
In the icy waters around Antarctica, some fish have evolved a truly unique trait, transparent blood. These icefish lack hemoglobin, the protein that gives blood its red color and helps carry oxygen. Instead, their cold environment holds enough dissolved oxygen to survive without it. Their blood is rich in antifreeze proteins too, which keeps their internal fluids from freezing. “They’re marvels of adaptation,” says marine physiologist Kristin O’Brien. It’s strange, sure, but also efficient. In the chill of subzero seas, these ghostly fish remind us that even the weirdest solutions can work.
12. Male Jawfish Carry Their Babies in Their Mouths
In a world where parenting roles vary wildly, male jawfish offer a tender twist. After fertilization, they carry their partner’s eggs in their mouths for protection until the babies hatch. Sometimes this goes on for up to 10 days. During this time, the male doesn’t eat and is completely focused on keeping the brood safe. “It’s full-time dad duty with no snack breaks,” jokes marine biologist Ethan Lin. This gentle form of caregiving might seem surprising coming from a fish, but it’s a reminder that fatherhood can take many forms. Even one with a mouthful of swimmers.
13. Some Fish Live in Acidic, Boiling Water
If you think boiling acid sounds unlivable, some fish would disagree. The Devil’s Hole pupfish and certain species in hot springs around the world survive in water that’s highly acidic and near boiling. These environments are typically lethal, but these fish have adapted their metabolism and biology to cope. “They’re extremophiles, living on the edge,” says biochemist Laura Vickers. It’s astonishing and humbling. As we wrap up, one thing’s clear. Fish are endlessly inventive in their fight to thrive. And if they can make it anywhere, maybe we can too.
This story 13 Weird and Wonderful Fish Facts You Definitely Didn’t Know was first published on Daily FETCH
