Yellow Boxfish

Yellow Boxfish

The Yellow Boxfish is another of the great variety of fish and marine life that Koh Tao diving has to offer.


Ostracion cubicus can reach a maximum length of 45cm, the ones I have seen here while diving on Koh Tao have been no more than 10cm, bright yellow and cute.

Boxfish are also known for their armored and rigid (box) body which in most cases makes it hard to move but it has evolved it’s own style of swimming called ostraciiform locomotion.  The body is made from armour plates with holes for the eyes, mouth, tail and fins.  When young it is bright yellow in color and as it grows and gets older the brightness fades and very old specimens will have blue-grey to black colouration with faded yellow.  They are solitary fish except at breeding time in spring when males hang round with up to 4 females.  Their diet is mainly marine algae, worms, sponges, crustaceans, molluscs and small fish.

Where can you find it on Koh Tao?

The Yellow Boxfish are hard to find on the dive sites around Koh Tao, I’ve seen them the most at White Rock dive site hiding in the staghorn coral with their little fins going.  But they can be found around Asia, the Indian and the Pacific oceans.

What do they do?

It looks small and cute but when injured or stressed it releases the neurotoxin tetrodoxin (TTX) from its skin that may prove lethal to the fish in the surrounding waters.  The bright yellow color and black spots are a form of warning coloration to any potential predators.  They can be very frustrating to divers and photographers as they go deeper into corals and holes when approached.  If you are looking to take a photo approach slowly so as not to spook it.  Being careful of your buoyancy and equipment so you do not damage the marine environment or equipment.

You can find out more about learning to identify fish by studying the Fish Identification course online.

What next for Koh Tao Diving?

So if you are interested in Koh Tao diving contact us and you can find out more about the diving we offer by clicking on the links below:

What other scuba certifications can I get on Koh Tao?

Want to know more?

How do I get to Koh Tao?

When is the best time to dive on Koh Tao?

Find out more about SSI here: Dive SSI


How to choose a Koh Tao diving school

Check out the SSI website.
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