Danio rerio

Danio rerio is very widely distributed species with a few populations threatened from overexploitation for ornamental fisheries.  Otherwise, the species is not threatened in its entire range and with the recommendation of continuing monitoring of population trends, it is assessed as Least Concern presently.

It is difficult to assess the population of the species. It is not common in the natural water bodies. It breeds easily in nature. Aquarists have also artificially bred the fish successfuly. In Nepal the catch per unit effort (CPUE) of this species is up to 1.88 %. In Arunachal Pradesh the catch rate is 1.9 % (Tamang et al. 2007).

The species is an annual species. Adults inhabit streams, canals, ditches, ponds and beels occur in slow-moving to stagnant standing water bodies, particularly rice-fields and lower reaches of streams common in rivulets at foot hills. Feed on worms and small crustaceans,  also on insect larvae. Breed all year round. Spawning is induced by temperature and commences at the onset of the monsoon season. Food availability also acts as cue for breeding.

Being a popular aquarium fish, it might suffer from over exploitation resulting in fluctuation of individuals.

Although it has been reported from Namdapha National Park, Arunachal Pradesh, it is also distributed in many unprotected areas. Thus, clearly there is a need for improved habitat protection at sites where this species is known to occur. Further survey work is needed to confirm whether or not this species is experiencing a widespread decline, or is undergoing extreme population fluctuations.

Hamilton, F. 1822. An account of the fishes found in the river Ganges and its branches. Edinburgh & London.

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.4). Available at: http://www.iucnredlist.org. (Accessed: 27 October 2010).

Jha, B.R. 2009. Fish ecological studies in assessing ecological integrity of rivers: Application in rivers of Nepal. VDM Verlag Dr. Muller Aktiengesellschaft & Co. KG, Germany.

Shrestha, J. 1978. Fish fauna of Nepal. Journel of NAtural History Museum Tribhuvan University. 5(1-4): 33-43.

Tamang, L., Chaudhry, S. and Choudhury, D. 2007. Ichthyofaunal contribution to the state and comparison of habitat contiguity on taxonomic diversity in Senkhi Stream, Arunachal Pradesh, India. Journal of the Bombay Natural History Society 104(2): 170–177.