Treasures in Aquatic Biota of Ceylon – Endemic fishes

Sri Lanka is a natural paradise in this world as it contains high biodiversity in both terrestrial and aquatic environments. Most of the tourists visit “Thaprobana” or Sri Lanka, to observe unique creatures who dwell in wildlife sanctuaries such as Yala, Kumana, Minneriya, Udawalawe, Gal Oya, Bundala, Sinharaja, etc. However,  most of the visitors are mainly focusing on terrestrial vertebral living beings (the animals who have backbones) such as leopards, elephants, deers, birds, and invertebrates like insects (especially butterflies). Therefore, they miss the enjoyment of observing these eye-catching fishes who can only find in the aquatic biota of Ceylon. 

Have you “truly” seen a fish?

No one will say “No” to the above question, except people who are born with the blind. In childhood, we indicated water by drawing swimming fishes. Those fishes would have been in various sizes, various colors and if you are more artistic you might have changed the shapes of their fins. However, it is important to know the basic anatomy of the fish, if you are interested to know about these aquatic treasures.

Fish (or Pisces) is the very first ancestor of the human being. According to the Darwinian theory, amphibians evolved from these fishes. Reptiles who evolved from amphibians showed more adaptations to terrestrial life and with the evolution, mammals, and birds evolved from these reptiles. It is very important to know that mainly there are two groups of fishes; Chondrichthyes (cartilage fishes such as sharks, skates, and rays) and Osteichthyes (bony fishes). We can see a large diversity of bony fishes in both marine and terrestrial aquatic environments as their bodies seem successive adaptations for various aquatic habitats. 

Their fusiform shaped body covers with various types of colorful scales. Their backward fins and body shape help to swim easily through the water. They use gills for respiration, instead of lungs and a special organ called swimbladder (which only can find in bony fishes) is one of the most significant features as it foremost helps to control the upthrust of the body. The capacity of the swimbladder determines the territory of the fish since it works as the pressure control unit of the bony fish’s body. The lateral line gives the sense to this creature about its locomotion. 

Anatomy of the bony fish

You may realize that the mother of nature has created our world with a scientific reason but in an artistic way. 

Endemic fishes of Ceylon

Most of them are red-listed by IUCN

The breathtaking biodiversity of Sri Lanka compromises with 53 endemic freshwater fish species out of 95 species of freshwater fishes. According to Sri Lankan ichthyologists, 70% are endemic fishes out of 41% of all fishes who dwell in Sri Lankan freshwater biota. But unfortunately, most of them are red-listed by IUCN as in the endangered category. The endemic species only can be found in a particular area of a country from the entire world. Hence, if they lose their habitat, that species will extinct forever. However, here you may find only a few of the endemic freshwater fishes who live in this small gorgeous paradise.


genus Channa

Snakehead fishes (genus Channa) are predators who native to freshwater habitats in Asia and C.ara Deraniyagala and C. orientalis (Ceylon snakehead) are endemic to Sri Lanka. Both of them are dwellers of the Mahaweli river basin. Like other members in this group, they are mouthbrooders (holding their offsprings inside of their mouth for incubation /oral incubation); hence you may see them as grumpy faced fishes.



Barbs and true minnows and their relatives are included in the family of Cyprinidae. There are several endemic barbs (genus name – Barbus) or “Pethiya” considered as aquarium fishes, due to there colorful scales. B.cumingi (Cuming’s barb) is a silver-colored aquarium fish dwelling in hill streams. This fish can be easily recognized among other barbs from two thrombosed black patches dispersed on the lateral line. If you have seen a purple head barb (B.nigrofasciatus) you may remember a shiny black ruby stone, thus it also is known as a black ruby barb. This ravishing fish can be found in the Mahaweli river (near Ginigathhena region).

Cuming’s barb (B.cumingi)
Black Ruby/Purple head barb (B.nigrofasciatus)

Sometimes ichthyologists introduce species to other countries that have similar environments to their habitats. Cherry barb or B.titteya is an example of the endemic species that has introduced Mexico and Colombia. This species and side black lined barb (B.pleurotaenia) can be found in the Mahaweli river basin. 

Cherry barb (B. titteya)
Side black lined barb (B. pleurotaenia)

Perly rasbora (Rasbora vaterifloris)  is also known as fire rasbora or vateria flower rasbora due to his enchanting color of scales. The habitat of this species is restricted to the Kalu river basin. If you are collecting stamps as a hobby, you may found some endemic creatures are included in those stamps, and mountain Labeo is one of the examples for that. “Gadaya” or Green/mountain Labeo (Labeo Fresheri) was one of the species who dwelt in the Mahaweli River basin. Unfortunately, scientists believe that this species may already be extinct. 


belantia Genus

“Gouramis” or Belantia genus is one of the famous aquatic fishes who native to freshwater habitats in South Asia. Ceylon comb tail or B. singata is extraordinary fish as it can be survived in low oxygenated freshwater as it has rudimentary lungs, in addition to gills. Malpulutta kretseri is another endemic species known as Ornate paradise fish or spotted gourami. You can observe this species in shaded slow-flowing steams. However, Both of these fishes can be found in the Mahaweli river basin.

Ornate paradise fish (Malpulutta kretseri)
Ceylon comb tail (B. singata)


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“Pulli ahirawa” or Jonklaas’s loach or the spotted loach (Lepidocephalichthys jonklaasi) is a family member of true loaches who are restricted to the wet zone of Sri Lanka. This marvelous yellowish fish also can be seen in Ceylon stamp collection.

Spotted loach (Lepidocephalichthys jonklaasi)

Protecting these wonderful creatures is a mandatory responsibility of every human being as all of us are children of our mother nature.


  3. Eric D. Wikramanayake, Conservation of Endemic Rain Forest Fishes of Sri Lanka: Results of a Translocation Experiment, Conservation Biology, Volume 4, No. 1, March 1990   

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