Piranhas
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40 free Piranhas trivia questions with answers — trivia quiz, new questions added Oct 2026.
Piranhas have one of the scariest reputations in the animal kingdom: razor teeth, feeding frenzies and rivers you would never dare to swim in. The real fish is stranger and far more interesting than the monster of the movies, and the best fun facts about piranhas start with how much of that reputation is myth. This quiz covers piranha teeth and bite, what these fish actually eat, how they breed, communicate and stay safe, where they live, their closest relatives, and the films, games and legends that made them famous. It is written for curious kids, families, teachers and anyone who enjoys animal trivia. Every question comes with a short explanation, so you pick up a new piranha fact whether you get it right or wrong.
30 of 40 questions with answers and explanations. Play the quiz
Q 01Which former US president's 1914 book cast piranhas as vicious killers after a trip to Brazil?
Theodore Roosevelt
Theodore Roosevelt watched a school strip a cow to the bone within minutes. Local guides had staged the show, penning the fish in and starving them first.
Q 02Research on red-bellied piranhas found that they gather in shoals mainly for which purpose?
Self-defense
Self-defense is the point: a shoal shields each fish from cormorants and caimans. Scientists who expected cooperative hunters found shy fish hiding in a crowd.
Q 03CT scans confirmed that piranhas shed and regrow their interlocking teeth in which unusual pattern?
One side at once
One side at once is how the teeth go, because they lock together like one long blade. Replacements grow underneath first, so a piranha is never left toothless.
Q 04Which blockbuster director's first feature was Piranha II: The Spawning, which he largely disowned?
James Cameron
James Cameron took over after the first director was fired, and the fish in his sequel can fly. He prefers to call The Terminator his first film.
Q 05Red-bellied piranhas, which mostly eat weak, dying or dead animals, are likened to which birds?
Vultures
Vultures do the same clean-up job on land. Far from being relentless hunters, these piranhas are generally timid scavengers that pick off what is already doomed.
Q 06Which activity in the water attracts piranhas, so that children are bitten more often than adults?
Splashing
Splashing draws piranhas in, as does the commotion of struggling fish near anglers. Some beaches in risky spots are fenced off with barriers.
Q 07The low-budget 1978 horror film Piranha cashed in on which blockbuster released three years earlier?
Jaws
Jaws inspired a wave of cheap imitations, and its own director called Piranha the best of them. His praise helped head off a lawsuit from the studio.
Q 08Shoals of red-bellied piranhas have been known to feed on animals as large as which giant rodent?
Capybara
Capybara can end up on the menu, as can wading birds such as egrets. Even so, piranhas mostly take animals that are already injured or dead.
Q 09Which plant-eating piranha cousin, with squarer teeth, is often mistaken for one in US waters?
Pacu
Pacu are mostly vegetarian and can grow far bigger than any piranha, reaching up to 88 pounds. Many reported piranha catches turn out to be pacu.
Q 10Piranhas carry their razor-sharp teeth in which pronounced jaw alignment?
Underbite
Underbite is the classic piranha look, with a strong lower jaw that sticks out. Their vegetarian relatives have squarer, straighter teeth and a much milder bite alignment.
Q 11Most piranha teeth have three cusps with a larger middle one, giving each tooth which overall shape?
Triangular
Triangular, flat and blade-like, the teeth are built for puncturing and shearing. One rare species, the lobetoothed piranha, has five cusps on each tooth instead.
Q 12A red-bellied piranha's razor-sharp teeth are usually hidden from view by which facial feature?
Thick lips
Thick lips, fleshy enough to cover the teeth, give a resting piranha a surprisingly mild face. Beneath its high forehead sit the powerful muscles that drive the bite.
Q 13How are the sharp, tightly packed teeth of true piranhas arranged along the upper and the lower jaw?
A single row
Q 21Piranha bites on swimmers become more likely in which part of the year, when food is scarce?
The dry season
The dry season lowers the water and packs piranhas into dense, stressed groups. Warning signs are sometimes posted at the riskiest swimming spots.
Q 22Although piranhas are sold as food at market, fishers often call them a nuisance for which habit?
Stealing bait
Stealing bait is only the start: piranhas also eat hooked catches and damage fishing gear. They may bite the fisher too when hauled in by accident.
Q 23Besides carving wood, some peoples of Brazil and Bolivia use piranha teeth for which grooming task?
Cutting hair
A single row on each jaw is the piranha trademark, with small cusps locking neighboring teeth together. Their plant-eating relatives carry a double row up top.
Q 14A red-bellied piranha lifted from the water makes which sound with muscles around its swim bladder?
Drumming
Drumming is the piranha's protest, a low-pitched sound made by fast-twitching muscles. In the water, the fish use different calls for face-offs, food fights and chases.
Q 15The wimple piranha has one of the narrowest diets known, with adults eating almost entirely what?
Scales
Scales are knocked loose when the wimple piranha rams another fish, then scraped off and swallowed. The attack leaves the flesh underneath undamaged.
Q 16A good share of a wild red-bellied piranha's diet is which body part, nipped from larger fish?
Fins
Fins nipped from the tails of bigger fish are a staple snack. Piranhas in aquariums nip each other too, and the damage grows back surprisingly fast.
Q 17Red-bellied piranhas dig shallow nests in flooded margins and attach their sticky eggs to what?
Water grasses
Water grasses hold the eggs, which hatch after just two or three days. The young then hide among the stems until they are big enough to look after themselves.
Q 18Before they are large enough to tackle small fish, what do newly hatched piranhas feed on?
Zooplankton
Zooplankton, the tiny animals adrift in the water, are a hatchling's first meals. The eggs are laid in pits that the adults dig and then patrol.
Q 19A 1585 dictionary of Brazil's Old Tupi first recorded the word behind 'piranha' as which tool?
Scissors
Scissors was the translation given, two years before a Portuguese explorer first applied the name to the fish. English had borrowed the word from Portuguese by 1710.
Q 20Which pink freshwater mammal, known in Brazil as the boto, eats piranhas among dozens of fish?
River dolphin
River dolphin diets are the most varied of any toothed whale, covering at least 53 kinds of fish. Adults turn pink as their skin is scuffed over the years.
Cutting hair is one traditional job for the razor-edged teeth. They have also been used to sharpen hunting darts.
Q 24How does the adult black piranha, a hunter of deep river channels, normally live?
Alone
Alone is the rule for this red-eyed species, which is not a sociable fish. For its weight, it has one of the most forceful bites measured in any vertebrate.
Q 25In one review, which Venezuelan river basin ranked second to the Amazon for piranha species?
Orinoco
Orinoco waters held 16 of the review's 38 or so species, against 25 in the Amazon. Seven kinds of piranha share just one stream in the country.
Q 26Piranhas are characins, which makes them relatives of which small, popular aquarium fish?
Tetras
Tetras and piranhas sit in the same order, Characiformes, which holds more than 2,000 species. Over 200 of them live in Africa.
Q 27Which peaceful, mostly plant-eating aquarium fish belong to the same subfamily as the piranhas?
Silver dollars
Silver dollars sit in the piranha subfamily but are not called piranhas, thanks to their largely vegetarian diet. In a tank they will often eat every plant.
Q 28The piranha family's scientific name joins the Latin for 'saw' to the name of which fish?
Salmon
Salmon gives Serrasalmidae its ending: the name means 'serrated salmon family'. The saw is the jagged keel running along the belly of these fish.
Q 29Chemists' 'piranha solution', which devours organic residue, mixes hydrogen peroxide with what?
Sulfuric acid
Sulfuric acid and peroxide together strip organic residue from surfaces such as silicon wafers. The mix can dissolve fabric and skin just as easily.
Q 30In Nintendo's Mario games, the toothy Piranha Plant usually emerges from which green objects?
Warp Pipes
Warp Pipes have hidden Piranha Plants ever since Super Mario Bros. in 1985. The plant later became a playable fighter in Super Smash Bros. Ultimate.