When a calm aquarium meets curious scientists or tipsy party‑goers, the water can turn into a stage for some truly odd tales. This collection of the top 10 weird fish stories shows how a simple tank can become the backdrop for baffling medical cases, bizarre experiments, and outright surreal mishaps.
10 Infectious Fish Pedicures
One of the latest buzz‑worthy wellness trends involves dipping your feet into a shallow pool teeming with tiny Garra rufa fish that nibble away dead skin, offering a surprisingly gentle exfoliation.
In a 2018 case from New York, a woman let these fish munch on the skin of her toes. Several months later, she noticed a split in her toenails, exposing the underlying nail plate.
Because the sensation was painless, she delayed seeking medical help for half a year. Eventually, doctors diagnosed her with onychomadesis – a condition where nail growth halts and the nail eventually falls off. After eliminating other causes, the clinicians linked the problem directly to the fish pedicure.
Previous studies have shown that Garra can harbor bacteria capable of causing skin and tissue infections. Hygiene is another concern: the communal tubs are difficult to sterilize between users, raising the risk for people with existing foot ailments who might be exposed to contaminated water.
9 Oldest Fish In Captivity
In 2018, a venerable Australian lungfish residing at San Francisco’s Steinhart Aquarium celebrated a milestone: roughly 80 years of life, with estimates nudging closer to 90 since she entered the collection as an adult in 1938. Affectionately named Methuselah, she stretches to about 1.2 meters (4 ft) in length.
This senior citizen of the sea enjoys a diet of figs and prawns, relishes belly rubs, and seems to have favorite staff members. When curators tried moving her into a larger tank with two younger lungfish, she stubbornly hovered upside down until they restored her to her original enclosure.
Lungfish are ancient survivors, tracing their lineage back 400 million years. They possess a unique swim bladder that doubles as a lung, allowing them to gulp air. Some species even “walk” across land in search of new water bodies.
Methuselah appears content with the prospect of reaching a century. Keepers note she eats heartily, enjoys human interaction, and has earned the nickname “underwater puppies” for her playful demeanor.
8 Fish Have Personalities
In 2015, researchers set out to answer a puzzling question: do fish possess distinct personalities? Their answer came via a series of staged scares. Guppies were exposed to a faux heron beak that plunged into their water, and later to “Big Al,” a carnivorous cichlid that suddenly appeared on the opposite side of the glass.
Each guppy, after being transferred to the “scare tank,” was left with only a tiny plastic shelter. Once the initial fright subsided, the fish was returned to a protected environment with many conspecifics. After three days, it was placed back in the scare tank for a five‑minute terror session, and this routine continued for a month.
After subjecting 105 guppies to this protocol, scientists observed that each individual displayed a consistent behavioral pattern—some hid, others fled, and a few froze. These repeatable responses indicated that the fish were not merely reacting randomly, but rather exhibiting personality traits.
The findings demonstrated that fish, much like mammals, can have individual behavioral signatures, challenging long‑standing assumptions about piscine simplicity.
7 Catfish Drinking Game
In a 2016 incident in Rotterdam, a 28‑year‑old man stumbled into the emergency department with a bizarre injury after a night of heavy drinking. Earlier that evening, he and friends decided to swallow live aquarium fish for fun.
While gulping several goldfish went smoothly, a teammate suggested trying a small catfish from the tank. The species turned out to be Corydoras aeneus, a armored catfish equipped with venom‑laden spines that stiffen when the fish feels threatened.
The spiny catfish lodged itself in the man’s throat, causing him to cough up blood and beer but no fish. His friends attempted an improvised Heimlich maneuver, then tried to wash the creature down with more beer, ice cream, and honey. After several hours of worsening symptoms, he finally sought medical attention.
Surgeons performed a delicate operation to extract the dead catfish. The specimen was later preserved at the Rotterdam Natural History Museum, joining a collection that highlights extraordinary human‑animal encounters.
6 Wrasse Recognize Themselves
A classic test of self‑awareness involves placing a subject before a mirror with a colored mark on its body; if the animal tries to investigate or rub the mark, it suggests recognition of the reflection as itself. Species that have passed include dolphins, chimpanzees, elephants, pigeons, and crows.
In 2018, scientists turned to the cleaner wrasse—a fish that feeds on parasites—to see if it could also pass the mirror test. Because wrasse are naturally attuned to odd spots on other fish, they seemed ideal candidates for self‑recognition studies.
When ten wrasse were isolated in individual tanks with mirrors, their initial reactions were aggressive, mistaking their reflections for rivals. After a few days, however, the fish began performing a peculiar “friendly dance” in front of the glass.
Although wrasse are typically solitary and do not dance for conspecifics, researchers hypothesize the behavior was a way to examine their own movements. When a colored gel was applied to the fish’s heads—visible only in the mirror—seven of the ten spent more time interacting with their reflections or rubbing the marked area against tank objects.
5 Fish Floaties
Leafy sea dragons, relatives of seahorses, are draped in leaf‑like appendages that make them look like floating seaweed. In 2018, the Florida Aquarium in Tampa welcomed three juvenile sea dragons, only to discover a troubling pattern.
The aquarium’s veterinarian observed that the youngsters were feeding poorly and consistently sinking to the tank floor, contrary to their natural buoyant lifestyle.
Further investigation revealed that all three suffered from a developmental defect: an under‑developed swim bladder, the organ responsible for maintaining neutral buoyancy. Without it, the dragons could not stay aloft.
Ingeniously, the vet crafted custom floaties using black neoprene rings, which are both buoyant and resistant to saltwater. The rings were looped around each dragon’s midsection and sewn together, allowing the fish to float, resume feeding, and grow normally.
4 The Stickleback C‑Section
Stickleback females normally release eggs that males fertilize externally; there is no internal gestation. In the 1950s, a pregnant stickleback was found in Scotland, but it received little scientific attention. In 2016, researchers revisited the phenomenon and located a heavily pregnant female.
Because the fish was nearing death, it was humanely euthanized, and a cesarean‑style extraction was performed to retrieve the developing embryos. Remarkably, all the embryos survived, were incubated in the lab, and eventually grew into healthy adults.
Genetic analysis confirmed that the offspring were not clones; they possessed genetic material from both parents. The most plausible explanation is that the female swam through a dense cloud of sperm, allowing fertilization through her egg tube.
Furthermore, female sticklebacks appear to have taken over a male‑typical role: normally, fathers fan the eggs to provide oxygen. In this case, the mother’s body somehow supplied the necessary aeration, enabling normal development.
3 Robot Guppies
Trinidadian guppies display a striking eye‑color shift: normally silvery eyes turn jet‑black within seconds when the fish becomes angry. Curious researchers built lifelike robot guppies to investigate whether this visual cue was intentional communication.
Using a deceased specimen, scientists crafted silicone replicas that could be fitted with either silver or black eyes. Tiny motors gave the models realistic swimming motions, and the robots were positioned near food sources to observe live guppy reactions.
Observations showed that smaller guppies approached the robot when its eyes were silver, but a black‑eyed robot triggered what researchers termed “honest aggression”—a clear signal that the fish was ready to fight and defend a valuable resource.
When larger, real guppies encountered the robot, they aggressively attacked it, attempting to seize the food and intimidate the smaller fish displaying the black‑eye warning. The exact physiological mechanism behind the rapid eye‑color change remains a mystery.
2 The Sandwich Ray
At Macduff Marine Aquarium in Aberdeenshire, staff were cleaning a tank that housed several thornback ray egg cases, known as mermaid’s purses. After the hatchlings had emerged, the empty cases were being removed.
When an employee attempted to extract air from one of the purses, the case wouldn’t collapse. Peeling back part of the shell revealed an unhatched ray trapped inside.
Because the original egg case was damaged, the team needed an alternative incubator. They ingeniously placed the embryo inside a sturdy sandwich bag, which acted as a surrogate shell for the next two months.
During this time, the ray developed normally and eventually “hatched” from the plastic. Once ready, staff transferred the young thornback to a tank with ten other rays, where it thrived without any apparent lingering effects from its unconventional upbringing.
1 The Abandoned Shark
In 2012, a wildlife sanctuary on the outskirts of Melbourne, Australia, was shut down after authorities discovered the operator was running an illegal animal park under the guise of protecting a giant earthworm species.
Among the creatures housed there was a great‑white shark, intended to be a temporary resident while its permanent home was prepared. When the park changed ownership, the new managers kept the shark.
Following the sanctuary’s closure due to violations, the remaining animals were transferred to the RSPCA. The shark’s fate took a macabre turn: it ended up preserved in a tank of formaldehyde, its 4‑meter (13‑ft) body suspended in a greenish liquid.
The eerie display quickly went viral, with urban explorers filming the motionless predator and uploading the footage to YouTube, turning the abandoned shark into an internet sensation.
Why These Top 10 Weird Fish Tales Matter
Each of these bizarre accounts highlights how aquatic life can intersect with human curiosity, mishap, and ingenuity, reminding us that the underwater world is full of surprises waiting to be discovered.