Finding Nemo introduced millions to the technicolour world of coral reefs.  

But beneath its heartwarming tale of family reunion lies a treasure trove of marine biology – some spot-on, some wildly imaginative. Let’s dive in and separate the science from the storytelling. How accurate is Finding Nemo?  

Let’s start by identifying some of the main characters.  

Who are the fish in Finding Nemo?  

The clownfish 

Nemo and Marlin are orange clownfish or clown anemonefish (Amphiprion percula), and their home-bound lifestyle is spot-on. Unlike their cartoon counterparts gallivanting across the Ocean, real clownfish are the ultimate homebodies. Adult clownfish rarely venture more than a few metres from their host anemone, making Marlin’s anxiety about Ocean exploration biologically justified rather than neurotic. 

What type of fish is Dory? 

Dory goes by a lot of names: regal tang, palette surgeonfish, blue tang, royal blue tang, flagtail surgeonfish, regal blue tang to name a few (Paracanthurus hepatus).  

Regal tangs like Dory are common throughout the Indo-Pacific, so her presence on the Great Barrier Reef checks out perfectly. However, her famous memory problems contradict everything we know about fish cognition. Studies show that P. hepatus can remember spatial layouts for months and demonstrate complex social learning. More on fish brains later.  

How accurate are the fish in Finding Nemo? 

Mr Ray the spotted eagle ray (Aetobatus narinari) makes a charismatic teacher, though real eagle rays are typically solitary creatures who’d probably skip group activities in favour of a solo swim.  

Gill the Moorish idol (Zanclus cornutus) represents one of the aquarium trade’s biggest challenges. These stunning fish are notoriously difficult to keep alive in captivity due to their specialised diet of sponges and tunicates (a group of marine invertebrates that include sea squirts which look, to non-divers like coloured blobs on the reef). This explains Gill’s dissatisfaction with captivity and desperate escape plans.  

The film shows a fish dropping their kids off to Mr Ray’s class using their mouth, representing one of nature’s most devoted parenting strategies.  

Cardinalfish (Apogon species) are the most common marine mouthbrooders, with males incubating eggs in their mouths for 8-10 days. This explains why they seem unable to speak clearly – try having a conversation whilst holding 200 delicate eggs in your mouth without swallowing. The cartoon, however, doesn’t look much like a true cardinalfish. 

Crush and Squirt are green turtles (Chelonia mydas), shown as current riding nomads, which is entirely accurate. Green turtles have been tracked making migrations of almost 3000km (1,864mi)!  

Our current estimates are that green turtles live to approximately 80 years old, so the claim that Crush from Finding Nemo is 150 is a bit steep. Turtles aren’t known to travel in family groups, but Squirt does show the independence of a baby turtle. Right from the egg, turtles are fending for themselves, which Squirt shows they are more than capable of.

Do sea turtles really cruise the East Australian Current? 

The East Australian Current (EAC) serves as nature’s highway in Finding Nemo, and this isn’t just Pixar imagination. The EAC is a genuine part of the Oceanic conveyor belt (global network of currents circulating water), flowing southward along Australia’s eastern coast at speeds up to 1.5 metres per second. 

Crush’s “express lane” concept isn’t pure fantasy either. Ocean currents do have acceleration zones, particularly near topographical features like seamounts and continental shelf breaks. These current jets can provide genuine fast-track transport for marine life, making the turtle highway a plausible, if simplified, representation of oceanic dynamics. 

Green turtles (Chelonia mydas) really do use these currents for epic migrations, though their navigation system is far more sophisticated than simple current-following. The sea turtles use magnetic field detection to create internal GPS systems, imprinting on magnetic signatures as hatchlings and using these for navigation throughout their lives. 

Are the vegetarian sharks possible? 

Bruce and his gang’s “fish are friends, not food” philosophy in Finding Nemo might seem biologically ridiculous, but nature occasionally surprises us.  

Bonnethead sharks (Sphyrna tiburo) can derive up to 62% of their nutrition from seagrass, making them the Ocean’s most successful vegetarian predators. These remarkable sharks have evolved specialised digestive adaptations to break down plant cellulose – essentially becoming underwater cows with teeth.

Whilst no shark is completely vegetarian (they still eat crabs, especially when they are older), the bonnethead’s plant-munching abilities suggest that Pixar’s gentle giants aren’t entirely impossible – just highly evolved.  

Other creature features in Finding Nemo 

Pixar’s attention to detail shines with creatures like the Spanish dancer (Hexabranchus sanguineus) – a spectacular sea slug that really does inhabit the Great Barrier Reef and can reach 40cm in length. These crimson beauties are nature’s underwater flamenco performers, funky reef rugs on a magic carpet ride over the corals.  

However, some characters are biogeographical impossibilities. They wouldn’t be in the same scenes.  

The anglerfish is most likely a black sea devil (Melanocetus johnsonii), the same species filmed swimming to the surface in early 2025. Whilst visually terrifying, the encounter represents a fundamental ecological error. These deep-sea specialists live 200-2,000 metres (656 – 6561ft) down, where they’d never encounter shallow reef fish. Our clownfish friends don’t usually stray below 15m (49,2 ft). The poor blobfish is a good example of what happens when you take an animal out of the pressure range it’s adapted to.  

Similarly, Nemo’s classmate Pearl is a flapjack octopus (Opisthoteuthis californiana). These are usually hanging out at depths of 200-1,500 metres (656 – 4,921 ft). These adorable cephalopods (who had a new species found in 2025) are built for life under crushing pressure and would be about as comfortable in shallow reef waters as a penguin in the Sahara.  

Let’s really get stuck in. Pearl talks about one of their arms (they say tentacles, but we know octopus have arms) being shorter than the rest. This means two things – that Pearl is a male octopus, and that arm is their hectocotylus, or an arm shorter than the rest that’s specialised to store and transfer sperm during mating.  

Finding Nemo got it wrong? Let’s talk clownfish reproduction and genders. 

Since we are ruining childhoods, let’s address the elephant seal in the room. Brace yourself for the biological bombshell that completely rewrites Nemo’s story. 

Clownfish live together in anemones, with the largest individual as the matriarchal female. The largest male mates with her, with other smaller males helping with the chores and waiting their turn.  

When Coral, Nemo’s mum, died in that barracuda attack, the real biological story would be different. Within 10-18 days, Marlin would undergo a complete sex change, transforming into Marlina – the new dominant female clownfish of the anemone. This isn’t just changing wardrobes; it’s a full hormonal makeover involving suppressed testosterone and elevated oestrogen. 

But would Marlina then mate with Nemo, as some marine biologists suggest? (Because Nemo was the only clownfish in the anemone.) Probably not. Studies show that clownfish larvae typically disperse 7-12 kilometres from their birth sites, and genetics prove most anemone families aren’t actually related. Marlina would more likely wait for a wandering young male to join the family and restart the dynasty properly. Thank goodness.  

Does Mr Ray actually teach anything? 

We love that Mr Ray’s impromptu biology lessons contain genuine scientific gems, though we do have notes. His Ocean zone definitions are accurate – the mesopelagic (200-1,000m or 656 – 3,280ft), bathypelagic (1,000-4,000m or 3,280 – 13,123ft), and abyssopelagic (4000m+ or 13,123ft+) zones represent real oceanographic divisions with distinct communities. 

His species song (it’s called ‘Let’s name the species’, if you want to look it up) is catchy and gives a fun overview of the species you can find on a coral reef.  

“Cnidaria” would be more accurate than “coelentera”. Coelentera is an old term grouping a lot of the animals he goes on to name: hydrozoa (hydriods like the Portuguese man-o’-war), scyphozoa (true jellyfish), anthozoa (coral and anemones) and ctenophora (comb jellies). Add in the porifera (sponges), byrozoa (colonies of moss animals), echinoderma (urchins and sea stars) and “some fish like you and me” and you have a pretty comprehensive overview of life of the reef.  

Mr Ray’s excitement about “stromalitic cyanobacteria” is understandable and surprisingly sophisticated for a children’s film. These layered rock formations, created by ancient cyanobacteria, represent some of Earth’s earliest life. They were crucial in the Great Oxygenation Event 2.4 billion years ago. We can thank them for introducing oxygen to the atmosphere! Even now, the Ocean provides around half the oxygen we breathe.  

Fish cognition: Smarter than we thought 

Dory’s memory issues might be Hollywood fiction, but fish intelligence is no joke. Recent research has revolutionised our understanding of piscine cognition. Fish can recognise individual faces, remember complex spatial maps, use tools, and even show signs of self-awareness. 

Cleaner wrasses (Labroides dimidiatus) pass the mirror test – a cognitive benchmark previously thought exclusive to mammals and birds. Meanwhile, archerfish demonstrate remarkable learning abilities, accurately spitting water at insects with ballistic precision that would make a sniper jealous. 

The idea that fish have three-second memories is complete codswallop. Goldfish can remember things for months, whilst cichlids can recognise their offspring years after separation. If Dory existed, she’d likely be suffering from a very specific neurological condition rather than general fish amnesia. 

(additional note – read What A Fish Knows By Jonathan Balcombe for more) 

Scientific pet peeves in Finding Nemo 

The blue whale 

The film shows Marlin and Dory falling to the back of the throat, to be blown out of the blowhole into Sydney harbour. But blue whales can’t blow something out of its blowhole from its mouth.  

A whale’s blowhole is linked to the lungs, nothing else. It isn’t spurting water out, it’s a mix of mucus and water on its skin (think blowing your nose when you’re wet). Scientists can actually find out a lot from a whale from its snot, and they use ‘SnotBots’ – drones to collect whale blowhole bits.  

The jellyfish 

The jellyfish in Finding Nemo aren’t really any specific jellyfish, just mash of a few features to create a generic jelly. The closest real-life versions are the maeve stinger (Pelagia noctiluca) or the Amakusa Jelly (Sanderia malayensis), but neither are a perfect fit.  

Despite the sound effects, they don’t electrocute their prey – they have small cells firing tiny needles loaded with venom into anything that touches them.  

Marlin claims “I am used to it”. There isn’t much science to say that would help. Remember Nemo brushing in the anemone before school? That is science! Clownfish avoid being stung as they have a protective mucus layer similar to the anemone (it has to avoid stinging itself). They brush up against the anemone to coat themselves in the mucus, keeping them safe from stings. But this is specific to their home anemone and wouldn’t help much against a smack of generic jellyfish. Marlin isn’t any more jellyfish-proof than any other reef resident. 

So, is Finding Nemo accurate? 

Finding Nemo succeeds brilliantly in capturing the wonder of marine life whilst taking considerable liberties with biological reality. Its greatest accuracy lies in depicting clownfish territorial behaviour and anemone relationships, whilst its most glaring errors involve biogeographical impossibilities that would make any marine biologist wince.

We can’t not mention how clownfish would actually react in Marlin’s situation – a biological reality that completely transforms the story’s foundation. It’s a perfect example of how nature’s truth can be stranger and more complex than fiction. 

Perhaps the real magic lies not in perfect scientific accuracy, but in inspiring curiosity about the Ocean’s genuine wonders. After all, reality is often far more extraordinary than anything Pixar could animate. 

FIN. 

Post by

Will Steen