Great Barrier Reef Fish so many interesting facts to discover

Australia’s Great Barrier Reef is home to over 1500 species of fish.  Great Barrier Reef fish come in more colours than one can believe exist.

Before describing all the different varieties of life on the Great Barrier Reef, it’s essential to understand how vast and diverse the range of creatures that live on coral reefs is.

All living animals are classified into 34 species (groups) in the animal kingdom.  The more species present in the ecosystem, the more different types of animals it supports and the greater its genetic diversity.

To give an idea of how diverse coral Reef ecosystems are, we can compare them to rainforests on land.  Rainforests cover an area 20 times larger than coral reefs.  However, rainforests have nine species in their ecosystems (including their rivers and lakes=17 different species), and coral Reef ecosystems support 32 of the 34 varieties.

Interest fact about Great Barrier Reef fish

The Great Barrier Reef is home to an incredibly diverse range of fish species, numbering in the hundreds of species. Here are some interesting facts about Great Barrier Reef fish:

  1. Clownfish, made famous by the movie “Finding Nemo,” are found in the Great Barrier Reef. They are known for their vibrant orange and white stripes and their symbiotic relationship with sea anemones.
  2. The Great Barrier Reef is home to the world’s largest species of bony fish, the ocean sunfish, which can weigh up to 2,000 kg.
  3. The reef is also home to the tiniest fish in the world, the Paedocypris fish. These fish are only about 7.9 mm long and can fit on the tip of your finger.
  4. The reef is also home to the highly venomous stonefish, which is known as the most venomous fish in the world. Its venom is so potent that it can cause paralysis and even death in humans.
  5. The Great Barrier Reef is home to the parrotfish, which has a unique feeding habit of grazing on coral. As they eat, they also ingest small pieces of coral, which they then excrete as sand, contributing to the sand on the beaches.
  6. The reef is home to a range of shark species, including the hammerhead shark, the tiger shark, and the whitetip reef shark.
  7. The Great Barrier Reef is also home to the brightly colored Mandarin fish, which is one of the most stunning fish in the world. Its vibrant colors and intricate patterns make it a favorite among divers and underwater photographers.
  8. Another interesting fish found in the Great Barrier Reef is the goblin shark, which has a long protruding snout and can extend its jaw to catch prey.
  9. The reef is also home to the majestic manta ray, which can have a wingspan of up to 7 meters. These gentle giants are a favorite among divers for their graceful movements

The Great Barrier Reef ecosystem is home to the following:

  • 400 varieties of corals
  • 4000+ species of molluscs
  • 1500+ species of fish- The Caribbean only has 900
  • 800 species of echinoderms
  • 1000’s species of sponges, worms and crustaceans
  • 22 species of seabirds live and breed on the islands inside the Great Barrier Reef marine park
  • 15 types of sea snake
  • Six of the seven marine turtles have been visiting the Great Barrier Reef.  The most common being the Green Turtle.
  • 30+ species of marine mammals visit the Reef, including Dugongs, Humpback whales, Minke Whales and Bottlenose dolphins.


Common species seen on the Reef sites

Make sure you take your time and look at the fascinating and fragile ecosystem of the Reef.  By having patience and respect for Reef life, you will see life and death before your eyes, builders and destroyers, allies and enemies all caught up in the battle for survival.


There are three main shapes of corals you may see while snorkelling or diving on the reef.  Within the shapes, a few common types can be seen.

Branched: Needle, Staghorn/finger, Knobby

Boulder: Brain, Honeycomb, golfball, bouquet, Lunar

Plate: Plate, Table, Basket, Slipper, Mushroom, Sheet (vase/cabbage/leaf)

Great Barrier Reef fish


Small and stocky, regular shaped.  They are territorial with their homes and can get aggressive when other herbivorous fish invade their territory.  Anenome fish are part of the damselfish family.


The smaller medium is cigar-shaped.  The tail is part of its body.  Swims like a bird flies.  They are carnivorous, but feeding habits among species vary considerably.


Disc-shaped blade(s)  n the body near the tail.  Distinctive frill on the tail.  I will see them nibbling algae on the coral or the sand.


Disc-shaped spine on the gill.  One of the few fish that are thought to form monogamous pairs for several years.


Disc-shaped, stripe over the eye, no spine on the gill.  They can form unstable pairs for a few years.


Circular-like body.  Quite often, broad or tall dorsal and anal fins are located toward the back end of their bodies.  One of the most friendly fish on the Great Barrier Reef.


Bottle-shaped, slightly flattened.  Swims along using rear fins (not tail) with the body rigid.  Triton Triggerfish can be aggressive during the breeding season.  If their dorsal fin is upright, you are in their territory, so best to swim away.


Brightly coloured with strong teeth resembling a beak, forming four plates.  Herbivorous.


The most common sharks to encounter on the reef are the small white-tip and black-tip reef sharks, which are not dangerous if left alone.

White Tip Reef sharks

White tip reef sharks are a small species of shark that are commonly found in coral reefs and shallow waters throughout the Indo-Pacific region. They are named for the distinctive white markings on the tips of their dorsal and caudal fins. White tip reef sharks are typically around 4-5 feet (1.2-1.5 meters) long, and are generally harmless to humans. They are active at night and rest during the day, often found resting in caves or under coral ledges. White tip reef sharks are carnivorous and feed on a variety of small fish, crustaceans, and cephalopods. They are an important part of the reef ecosystem, helping to maintain the balance of the food chain. While they are not typically dangerous to humans, caution should still be exercised when swimming or diving around them.

Unusual habits of reef fish

Learning a little bit more about some of the reef creatures, you will be able to appreciate what you’re looking at, as there are limitless amounts of quirky and exciting behaviour, colourful and creative creatures, all different shapes and sizes, and colours evolved to survive.

Learn more about the Great Barrier Reef and plan a trip with a marine biologist onboard companies employ marine biologists to educate visitors on how important it is to take care of the Great Barrier Reef.

Coral Spawning

One or two nights of the year in late spring/early summer, when the sea temperature warming combined with lunar cycles, the tides are at their weakest a few days after the full moon.  Around 300 species will simultaneously discharge their egg and sperm into the water column, which floats to the water’s surface, along with a few other organisms, such as the Christmas tree worm.  You could perhaps call it Earth’s biggest orgasm!

Most Reef animals are hermaphroditic, either simultaneously changing from female to male (most common) or male to female.

One fish that you are all likely familiar with is the clownfish- Nemo.  The system is how clownfish behave, and mate differs slightly from the movie.  At the beginning of the film, there is Marlon and his Wife; his wife dies, and so here is where things differ in the clownfish world.  Generally, there will be a female (the largest), a dominant male and a few immature males in a group of clownfish.  When the female partner dies, the dominant male (Marl n) would have changed to become a female.  Usually, the most prominent male of the immature males will become the male partner of the new female.  So in real life, Marlon would have turned into a female, and Nemo would have become Marlon’s new male partner.

Mutual symbiosis

Anemonefish/clownfish and Sea anemones have a mutually beneficial relationship.  The clownfish live amongst the anemone’s stinging cells, providing each other with defence.

Goby fish and prawns- prawns are blind,  o use gobies as a lookout to warn t e prawn.  The gobies, in return, have a home.  The prawn digs a hole big enough for both of them and regularly maintains it.  They use signals to warn each other, the goby waves its tail, and the prawn moves its antennae.

Cleaning stations- Cleaner wrasse and larger fish have total trust in each other.  The larger fish will approach the ‘cleaning station’ so the cleaning fish can clean it.  It will often have its gills, mouth and fins open to signal it wants to be cleaned of parasites and dead skin cells and w ll remain immobile to allow the fish to clean it.  Both fish benefit as the cleaner fish receive a meal, and the larger fish are clean of parasites and dead skin cells.  The average cleaner wrasse sees 2000 clients a day.  There are also cleaner prawns.


Triggerfish are like the big bad wolf in the three little pigs.  They can blow powerful water jets onto the sea bottom to uncover prey or overturn and render the harmless sea urchins/eggs they love to eat.

Nudibranchs gain most of their protection from their food; once they have devoured their prey, they re-use toxins from sponges and stings from hydroids and transfer them to the tips of their dorsal papillae.

Emporer shrimps live on many species of sea cucumber, starfish and nudibranch.  These animals don’t benefit from the emperor shrimp).  Charmingly they often feed on the faeces of their host, providing the ultimate recycling facility.

Colours of the Reef

Camouflage is used for defensive purposes, to hide or become invisible in the surrounding environment; some animals appear to have more prominent features or fake eyes on their bodies.  Some fish use bright colours will be used to warn that they are poisonous, mimic other toxic species, and show differences between adults and juveniles, male and female.  A lot of fish will change their colour to a more dull shade at night, so to hide from predators.


Many Reef animals, such as crocodile fish, flat fish, and stingrays, all have flat bodies, which is beneficial for their hunting strategy.  They will bury themselves in the sandy seabed and use surprise attacks to capture their prey.

Threats to the Great Barrier Reef

For millions of years since the evolution of the Reef, corals have survived many natural disasters and dramatic climate changes and still produce some of the most biodiverse ecosystems on earth.  However, with all the added problems and exploitation the human race has caused, the signs of how we l they will cope and survive shortly are not encouraging.  So we hope that your visit to the Reef will inspire you to preserve and help protect the coral reefs and their inhabitants, as such a complex and diverse ecosystem is so fragile.  Even the extinction of one species can cause a domino effect of destruction to many other species.  Here are only a few of the human-induced problems the Great Barrier Reef and other coral reefs of the world face.

Problems facing the Great Barrier Reef

    • -Global warming causing coral bleaching
    • -Pollution and development
    • -Overfishing
    • -Carbon dioxide acidification of the ocean stunting the growth of coral.
    • -Crown of thorn starfish
    • -Unsustainable tourism
    • -Habitat degradation

Other threats to coral reefs around the world

  • Dynamite fishing
  • Coral mining
  •  Mariculture

We are using Sodium cyanide to stun and capture Reef fish for the marine aquarium market.


Great Barrier Reef Marine Park Authority

First was established in 1975 to protect and manage the fragile ecosystem of the Great Barrier Reef.  The Great Barrier Reef is the best-managed and protected coral Reef in the world, although there still are threats to its survival.

Ways in which divers/snorkellers can help protect the Reef from damage

Awareness of the fragile animals of the Great Barrier Reef.

The only thing you should be taking from the reef is photos and memories.  A good policy to protect the reef and yourself is not to touch anything as it could destroy part of the Reef or potentially harm you as there are many poisonous organisms on the reef.

Know your body and equipment place ent, and keep your diving skills sharp.

Become an eco-tourist.  Try to avoid collecting souvenirs like corals or shells.

Next, explore our Great Barrier Reef tours to see which one suits you best.