The Most Popular Fish Species Around Koh Tao

Marine Life you'll see when diving around Koh Tao

The Most Popular Fish Species Around Koh Tao

Koh Tao is one of the most popular tourist and holiday destinations in Thailand. It is a hidden jewel in a country known for its sun kissed beaches, culture, and gastronomical experiences and of course for its splendid tropical and exotic diving locations.

Koh Tao is the ideal place to visit for short-term travellers and is world famous for learning to scuba dive and to experience underwater adventures. In a country that is famous for its magnificent creatures such as tigers and elephants, in this blog we take a look at the marine diversity below the surface of the sea.

Whale Shark

The whale shark is the largest living fish on our blue planet. It has a huge gray and white spotted body, with each set of white dots uniquely identifying each fish and is similar to their own “digital” DNA.

This giant fish of the sea can measure up to 14 metres in length with some individuals growing up to 20 meters. Despite its size, the whale shark is a harmless fish and is not known to be aggressive to divers. It moves very elegantly and at a slow and steady pace (about 5 km per hour) but is able to cross thousands of kilometers during its migrations.

It is generally rather solitary, although it is sometimes possible to observe groups in varied geographical regions during their breeding periods.

Sea Turtles

Turtles have a history dating back over 200 million years and have witnessed the dinosaur period and survived all the subsequent climate changes. Today, there are more than 293 species of turtles and they exist in areas such as open seas, rivers and on land. In recent years, the decline of the turtle population has accelerated.

Currently, about 42% of the species are on the verge of extinction.

In Koh-Tao we have set up marine conservation programs and educate and train our divers in a wide range of subjects such as the non-use of plastic bags and plastic straws that each year are responsible for the cause of many premature turtle deaths.

Blue Spotted Ray

There are many species of rays in the world. One of the most common species around Koh Tao is the yellow and blue spotted ray. The blue spots on its back give it a stunningly beautiful color.

They are related to the shark family because of their cartilaginous skeleton and their tails have rows of thorns. They also have a long spine that can reach up to 40 cm in length. The rays are one of the most graceful of fish around Koh Tao and are incredibly beautiful to watch whilst diving.


There are about 40 different species of Triggerfish and most of them are marked with lines and spots. They inhabit tropical and subtropical oceans throughout the world, with the greatest species diversity in the Indo-Pacific region.

Most are found in relatively shallow coastal habitats, particularly around coral reefs. It is worth noting that Triggerfish can be very aggressive when protecting their territory particularly around breeding season. With its unusual physique and unpredictable behavior it is a very interesting species of fish to observe and be cautious around.

Yellow Boxfish

This beautiful fish changes shape throughout its growth. The juvenile yellow boxfish has a yellow round shaped body with black dots and translucent fins. As they grow, their bodies lengthen and the female becomes yellow mustard with white spots, surrounded by a black circle and its fins are bright yellow.

The male adult has blue spots surrounded by black dots on a light brown or bluish background with blue fins speckled with black dots. They are extremely cute when they are small and can be carried along by the current. However, it’s worth noting these fish come with a severe health warning due to a release of powerful toxins when they get stressed.


Similar to the Yellow boxfish, this charming fish changes shape from a juvenile as it grows into adulthood. They are essentially nocturnal fish but can be encountered during the day.

The solitary adult individuals hide in caves, under rocky overhangs or large tabular coral beds. The young spend their time alone and behave differently. They are territorial and occupy a small, well-defined territory and swim with erratic movements giving the perception that they don’t know how to swim properly.

They have mimetic behavior and attempt to replicate the behavior of flat worms that are toxic as it helps to protect them from predators.

White Eyed Moray Eel

Found singly in coastal waters they feed on small fish and invertebrates as well as smaller eels. Moray Eelsopen and close their mouths to move water through their gills for respiration. This behavior can often be seen as a threat especially towards divers, in fact they are very shy creatures and can become aggressive if provoked.

An interesting fact is that the moray eel has two jaws that work independently from each other and is used when consuming their favourite prey.

Scribbled Filefish

This is the largest of Filefish in the species and are found on coastal reefs along slopes and drop-off’s and feed on invertebrates and algae. The body has an elongated shape to it with body coloration that is olive-brown or grey depending on its surrounding environment.

The Scribbled Filefish can change colors quickly depending on background and the environment in a similar way to an octopus. Although closely related to the Triggerfish, their “trigger spine” cannot be locked into place.

Longfin Batfish

The Longfin Batfish is one of the common names given to the ocean species Platax Teira. Their appearance is striking and their nature very curious, so don’t be surprised if you find them tagging along on your dive.

Longfin Batfish grow extremely fast compared to other fish and quickly reach their full size. The shape and the colour of the juvenile fish are different from the adult. Extensive research has shown they are intelligent fish and can recognise individual people. They are also known to form huge schools even with different species.

The diversity of marine life around Koh Tao provides divers with an opportunity to experience the local underwater world at its best. As a PADI Open Water diver or Advanced Open Water diver with Crystal Dive Koh Tao, you can explore this underwater wonderland up to the recreational depth limit of 40 metres.

Author: Marie Suzanne-Houbiers (PADI MSDT #370229)

Crystal Dive Koh Tao

7/1 Moo 2
Tambon Ko Tao
Koh Tao
Surat Thani

E-mail: [email protected]

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