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Nemos in North Sulawesi

Things You Never Knew: 8 Facts about Anemonefish

Anemonefish are so often over looked by divers but they are one of the most colorful and characterful fish in the ocean. Anemonefish have incredible symbiotic relationships with their hosts and they have some of the most intriguing behavioural patterns. Read on to find out more…

1. Species

Did you know that there are almost 30 species of anemonefish? They are from the family of Pomacentridae and the subfamily amphiprioninae. All species share some common factors including size (up to 18 cms) and markings (usually white stripes or bands).



2. Males and females

All anemonefish are born male. Anemonefish are hermaphrodites which means that they can change sex. Usually the largest and most dominant anemonefish you find on an anemone is actually a female and the smaller fish surrounding her are males. The largest male is the only one which she will mate with and when she passes away it’s this male which will change sex and take her place.

3. It’s all in a name

Where did the name “nemo” come from? Easy – it came from the host anemone – a“nemo”ne!

4. Aquarium trade

Did you know that since the release of the movie “Finding Nemo” anemonefish became the most sought after fish for the aquarium trade? Unfortunately the methods used to capture these beautiful little fish frequently involves the use of cyanide to stun them which makes them easier to catch.


anemonefish and anemone shrimp

5. Symbiosis

The anemonefish is one of the only marine creatures that can withstand the toxins of the anemones in which they live. Sea anemones are highly poisonous but the anemonefish is covered with a protective mucus membrane which keeps them safe.


The sea anemone, in return, protects the anemonefish from predators, as well as providing food through the scraps left from the anemone’s meals and occasional dead anemone tentacles. In return, the anemonefish defends the anemone from its predators and parasites.


The anemone also picks up nutrients from the anemonefish’s excrement, and functions as a safe nesting site. The nitrogen excreted from anemonefish increases the amount of algae incorporated into the tissue of their hosts, which aids the anemone in tissue growth and regeneration. It’s a match made in heaven!


black and white anemone photography


6. Hatchlings

Anemonefish will find a flat surface close to their host anemone and it is here that they will lay their eggs – usually hundreds of them. While the eggs are developing the male anemonefish will guard over them but once they are hatched they are left to defend for themselves and find their own anemone.

7. World-wide distribution

Anemonefish are found on shallow reefs in both the Pacific and Indian Oceans but they are not found in the Atlantic Ocean which offers fewer shallow areas and colder sea temperatures.

8. Isopods

Anemonefish don’t just work with their host anemones. Occasionally they also play host to “trespassers” of their own which are known as isopods. An isopod is a small parasite which you can often see on an anemonefishes tongue – usually you will just spot 2 small eyes. You have to pay close attention to see these tiny critters so next time you find an anemonefish look carefully – you might be surprised by what is looking back at you!


anemone fish and Isopod


We hope that you have enjoyed these facts and we’d love to show you some of the amazing anemonefish species that we have at our dive sites next time you are here. In the meantime, if you have any underwater images of anemonefish that you’d like to share with us please do so! We’d love to see them, so please send them in to For more information about our diving and some of the best dive sites in Indonesia check here.


Why not join us for a Passport to Paradise and explore North Sulawesi with seamless boat transfers from resort to resort? Bunaken, Bangka and Lembeh in one easy trip – no packing, no wasted transfer days, just dive your way around North Sulawesi and experience the best walls, reefs and muck that Indonesia has to offer. We are looking forward to welcoming you to Murex Manado and Murex Bangka Resorts soon.


Dive, Snorkel and Explore More with us in beautiful North Sulawesi.

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