''Garra ceylonensis'' (the stone sucker or Ceylon logsucker) is a species of ray-finned fish in the cyprinid family. It is endemic to rivers and streams in

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

(formerly known as "Ceylon") - and is considered as a schooling fish. It is a rheophilic species and occurs in slow to moderately flowing rivers and streams, and ascends small, rocky streams in order to breed. It primarily feeds on algae such as diatoms.

Taxonomy

A 2021 study found ''G. ceylonensis'' to be a sister species to the

mullya garra The mullya garra (''Garra mullya'') or sucker fish is a species of ray-finned fish in the genus '' Garra''. It is found in streams and rivers throughout India except for Assam and the Himalayas. Reports of the species from Nepal have not been ve ...

(''Garra mullya'') from mainland India, which itself may comprise two species. ''G. ceylonensis'' comprises primarily six genetically distinct

subclades In genetics, a subclade is a subgroup of a haplogroup. Naming convention Although human mitochondrial DNA (mtDNA) and Y chromosome DNA (Y-DNA) haplogroups and subclades are named in a similar manner, their names belong to completely separate syst ...

that are each tied to a single river basin, albeit with two exceptions.

Evolution

The ancestor of ''G. ceylonensis'' colonized Sri Lanka from India once during the late Pliocene, via a former isthmus that existed in the Palk Strait, and from the Pleistocene until its submergence, the still-exposed isthmus may have had a hydroclimate unsuitable to further dispersal of freshwater fish. During the Pleistocene, a major aridification event led to the extirpation of many ancestral ''G. ceylonensis'' populations, leading it to be restricted to several relict populations. When the climate became more suitable, the species recolonized most of the island, which may have been facilitated by

stream capture Stream capture, river capture, river piracy or stream piracy is a geomorphological phenomenon occurring when a stream or river drainage system or watershed is diverted from its own bed, and flows instead down the bed of a neighbouring stream. ...

and the species' free-swimming larvae.

Status

''G. ceylonensis'' is considered near threatened on the IUCN Red List. The species is frequently exploited for the aquarium trade, and there have been major changes to its habitat from deforestation and hydropower projects that block its migration routes.

References

{{Taxonbar, from=Q3758528 Garra Freshwater fish of Sri Lanka Taxa named by Pieter Bleeker Fish described in 1863