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clownfish eggs

Finding Nemo – The true story about clownfish

Everybody knows this little cute clownfish from the movie "Finding nemo". He got caught by divers and was saved  by his dad Marlin and their good friend Dori in the end . Now Nemo is one of the most famous fish which every diver wants to see.

But how much do you really know about this fish?
What is his real scientific name?
Do you recognize the other different types of them?
How can they survive in the poisonous anemone?
This special fish has a few interesting facts you should know.

Different Types of Clownfish

Nemo and his dad are false clownfish or clown anemonefish. Anemonefish because their home is the sea anemone which is actually toxic to all the other fish. False because they look similar to the orange ("original") clownfish. We have around 28 different species of anemonefish in many different colours like pink, red, black or brown with different types of stripes. However most of them are orange with three white bands on their body like little Nemo.

Toxic home

So what is so special about the fact Nemo and all other clownfish can live in the anemone? Anemones are creatures which anchor themselves in the sea floor and catch food with their tentacles. Be careful about these tentacles and never touch them! They have stinging cells which release a toxin when prey or predators touch them.
However, clownfish are immune to this toxin because they have a mucus layer they build up by touching the tentacles carefully. Nemo's dad always wanted him to stay in the anemone. That's because the symbiotic relationship gives them protection while the fish bring food to the anemone.

Is Marlin really Marlin?

Now, we have to tell you the truth: Actually after Nemo's Mum got eaten by a Barracuda his dad should have become a female. Why?
All clownfish are hermaphrodites. They are all born as male and can change their gender into a female. The largest dominant fish will become the female of the group.

So next time you watch an anemone and you see the biggest clownfish swimming at you, you know it’s the boss, the female. She's the leader, the protector. The second largest fish is the dominant male and the other from the group the smaller males.
Now if the female, like in the movie, gets eaten and dies, the dominant male will change his gender. He becomes the new leading female, replacing the dead one. Therefore, Marlin should have changed his gender after Nemo's mum died and turn into Marilyn and Nemo would have been the next dominant male. As this doesn't make for a great children's story, we are quite happy with what is told in the movie.

Small fighters

When you ever come close looking at an anemone you see the female one is coming near to your face and going back to the anemone, they do it a few times. What they try to do is making you afraid and banish you. In the movie they say clownfish are funny. No way they are funny, they are very defensive. They are protecting their home, their group, their eggs - fair enough. Never put your finger to a clownfish, they can also bite. They might be small, but oho... take care.
Their main food is plant and meat, like algae, zooplankton, worms and small crustaceans.

Strange noises

Maybe you already heard some strange noises coming from this little fish like popping and clicking. This is how they communicate. With this sound they prevent conflict between each other and maintain the rank of all group members. So, listen carefully the next time you’re diving!


How did Marlin get the attention of his super bossy wife to lay some eggs?
First, the male prepares a nest on a bare rock next to the anemone before spawning. Then he courts the female by showing her his extended fins also with biting and chasing her to the nest. After that it’s up to her to lay eggs (from 100 to 1000 eggs). After she's done, the male comes back to the nest to fertilize the eggs. The female swims away and the male is the one who's mostly taking care of the eggs. After 6-8 days the larvae floats away and spends about 10 days drifting until they become juveniles searching for a host anemone.
Nemo was lucky that his dad took care of him from the beginning on.

So you see, the story of Nemo is more interesting when you know more about it. Book your dive with us here in Zanzibar to see this beautiful fish for yourself!

International Year Of the Reef 2018

Fact: The world's coral reefs are under threat.
Question: What is threatening the reefs?
Answer: Human activities and changes in the natural environment cause an accumulation of stresses to the coral reefs.

The facts are clear! Unfortunately human impact has had devastating effects on the oeans. Therefore let us all strive to less impact in the oceans.

Fact: The year 2018 is the 3rd International Year of the Reef, IYOR2018.
Question: What initiatives are being pursued in Zanzibar for IYOR2018?
Answer: Lately, scientists and divers established the Zanzibar Reef Monitoring Network!

This network recently held a workshop in association with Marinecultures, Chumbe Island Coral Park and ZURI with the goal of enabling customised coral reef monitoring protocols for our reefs.
Along with changing our habits on land we can all participate in reef monitoring by snorkelling and diving.
Everyone can make a difference. When you visit us, ask us about our reef checks and if you can participate in one. Come join us on our trips and let us teach you how to observe the magic of the underwater world.

Question: What is the aim of the Zanzibar Reef Monitoring Network + participating in reef checks?
Answer: The Zanzibar Reef Monitoring Network are CORDIO’s eyes in Zanzibar as all the data collected will be analyzed by CORDIO’s scientists and will support CORDIO’s Theory of Change.

At One Ocean we firmly believe in educating not only our staff, but also our guests on the importance of protecting our coral reefs and the awareness of our own impact.

Let's all be the change we want to see.

plastic ocean

Life in plastic is not fantastic

How many times during the day do you use plastic objects?

If you care about the health of the planet and of the oceans, you are probably very careful when it comes to plastics usage. But are you sure you are doing as much as you can? Let’s picture a typical morning of an individual working in an office in the city. Let’s call him Paul and let’s invade his privacy a little ...

07:00 AM Alarm goes off, Paul gets up and goes for a shower to wake up. A bit of shampoo (1) and some shower gel (2), rinse it off and 10 minutes later he is done. Looking good in the mirror, but it’s time to shave. Done! As a final touch, a bit of that brand new after shaving cream (3). Some minty toothpaste (4) on his toothbrush (5) and he is ready to go.

Paul doesn’t like to have breakfast at home; he will quickly stop by that café on the way to work. The barman always gives him a little take-away cup (6) for his coffee. He knows Paul loves it sweet, so he makes sure that he is not missing a spoon (7) to mix it. Paul walks to work every morning because his office is just few steps away from home.

08:00 AM Paul starts his day in the office.

Now if we check quickly, Paul used seven (7!!) plastic objects in just an hour. Some of these objects are used only once and then thrown away. But you could easily replace them with objects made of recyclable materials, like glass bottles. Wouldn’t that be great?


The sum of plastic waste equals a terrible reality that many people pretend not to see. Huge amounts of garbage are threatening our oceans every day. Dirty and polluted seas are unwelcoming places and therefore, marine life is slowly deteriorating and disappearing. Somehow, some creatures survive in these conditions. But what’s the price they have to pay?


The term sea turtle is probably taking you somewhere sunny and tropical. Maybe the term straw makes you picture your favourite drink? Let us tell you the truth. "Sea turtle with straw”, is not the name of a new exotic cocktail you could order barefoot by the beach. It’s the description of a terrible discovery.

In August 2015, Costa Rica, a team of biologists decide to take immediate action when they find a male turtle having something stuck in its nostrils. What appeared to be a worm, sadly ended up to be a 10-centimetre long straw stuck in the nose of this poor animal. Still feeling thirsty?


Seahorse and cotton swab … there must be a typo here? Unfortunately, there is not. This incredible marine creature and this familiar object have something in common.

Late September 2017, photographer Justin Hofman’s image of a seahorse holding on to a cotton swab, spread on the Internet. He took the picture in Indonesia and it immediately became the symbol of ocean pollution. What could be a Photoshop masterpiece, is in fact just an extremely sad reality.


Don’t worry, we are not judging anyone – #stopsucking is just one of the numerous campaigns created to preserve our planet. It focuses on the massive (ab-)use of plastic straws in the US but is relevant anywhere in the world.

If you want to start some real action, here are few tips for you:
• In the digital era, forget selfies and use your phone to take action for a clean ocean!
• Even if maths is not your strength, you can surely count to nine.
• Check out this guide from Ecowatch on how to reduce, reuse, recycle and more!


At One Ocean we recently took a big step towards preserving the ocean. No more single plastic bottles on our boats! During our diving & snorkelling trip, our guests used to receive a bottle of water each. The result? We wasted a lot of water and threw a huge number of bottles away.

Therefore, we decided to get reusable cups. Our guests can refill them, as many times as they want, from a dispenser. We are reducing our waste significantly. Also, we serve our snacks on large plates that our staff carefully wash after every usage. We are also selling reusable water bottles if you want to take a souvenir home that can help saving the planet. Every little action can make a big difference.

Coral bleaching comparison

Coral Bleaching

At a time when the human race strives justifiably to recognize diversity and equality amongst ourselves, we can learn some lessons about coexistence from looking at the most diverse of marine ecosystems – coral reefs. Like our own civil rights and liberties, coral reefs also need to be respected, maintained and protected from the effects of human impact. Unfortunately they have suffered from coral bleaching in recent years. We'll tell you why we have to try and stop this process.

What are coral reefs?

Often called the rainforests of the sea, coral reefs are known to contain about 25% of the world's fish species…. Now there is coexistence and diversity for you.


There are 3 main types of reef structures:

  1. Fringing reefs, where they project seaward directly from the shore forming a border
  2. Barrier reefs, where they also form a border but at a greater distance from the shore. They generally have lagoon conditions in between
  3. Atolls, like our own Mnemba atoll, which form when reef grow around a volcanic island. The island subsides completely below sea level while the coral continues to grow upward, forming an atoll.

The formation and growth of coral occurs when free swimming coral larvae attaches itself to submerged rocks, hard surfaces and edges of islands. The coral polyps, when suitably attached, secrete a calcium carbonate forms the skeleton that is the. This base of all coral reefs. On the one hand the skeleton a building block for other corals to grow. On the other hand, it also offers protection to the coral and marine life that reside within and around it. Coral grows best in clear, shallow warm water, they need salt water and sufficient sunlight to survive.

What causes Coral Bleaching?

Two of the main factors that are affecting coral reefs are global warming and pollution. Coral bleaching is happening at an alarming rate threatening the survival of coral ecosystems. Rising sea temperatures due to global warming is one reason why corals bleach. Bleaching happens when corals exposed to extreme stress expel algae, which is a major source of food for the coral. This leaves the coral appearing white and pale and more susceptible to disease. Contrary to belief coral may not completely die when bleached and given the right circumstances can prevail. That said once bleached due to the stress they are under the chance of survival lessens greatly.


How can we prevent it?

Now more than ever we must make a choice to reduce our impact and our added effect to these environmental issues. By reducing our emissions, pollution run-offs into our water sources, use of plastics and overfishing we can not only help revive our ailing reefs but help them grow for future generations of marine life and humans to enjoy and live off.

As well as sustaining one quarter of fish life coral reefs can benefit local communities. Through education and the right practices, responsible tourism is one way in which a community can grow and develop by looking after the coral ecosystem.

At One Ocean, we firmly believe in not only educating our staff but also our clients. We emphasize on the need to follow safe diving and snorkelling practices and standards to help protect and learn about this amazing ecosystem.


One Ocean is partnered with Carbon Tanzania where we help offset our carbon footprint. You as a guest can help by donating to this wonderful cause.

Together we can all make a change.