Kryptopterus cryptopterus is a species of catfish

Catfish

Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

, the type species of the genus Kryptopterus

Kryptopterus

Kryptopterus is a genus of catfishes belonging to the family Siluridae. They are found in freshwater throughout Southeast Asia. The scientific name comes from Ancient Greek kryptós + ptéryx...

. It can be distinguished from all its congeners, with the exception of the newly split Kryptopterus geminus

Kryptopterus geminus

Kryptopterus geminus is a species of catfish belonging to the family Siluridae. It can be distinguished from all its congeners, with the exception of Kryptopterus cryptopterus, by the almost flat dorsal profile with no concavity behind the head....

, by the almost flat dorsal

Dorsum (biology)

In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...

 profile with no concavity behind the head.

This distinctively shaped, translucent fish is found in peninsular Malaysia, Borneo

Borneo

Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 and Sumatra

Sumatra

Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

. Specimens from Cambodia

Cambodia

Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...

, Laos

Laos

Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...

, Thailand

Thailand

Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

 and Vietnam

Vietnam

Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 previously assigned to this species are now recognized as a separate species, K. geminus. K. cryptopterus can be distinguished from this close relative by its broader head, shorter snout, shorter anal fin and eyes located much more ventrally.