Seoul, July 6 (IANS): South Korean authorities caught four piranhas in the water reservoir of a mountainous area this weekend, according to media reports.

This is the first sighting of these freshwater species, native to South American rivers, in the country, Efe news agency reported on Monday citing Korean media.

The carnivorous fish, that included a lethal red-bellied piranha, were captured between Friday and Saturday in a 10,000-square metre reservoir in Hoengseong county, 100 km east of Seoul in the northern Gangwon province.

The fish were first spotted by a local resident, who alerted authorities to the unusual presence of the exotic fish in the reservoir.

On Friday, the National Institute of Ecology launched an investigation and found a 19-cm-long piranha.

A day later it caught two more, both 15-cm long, as well as a 30-cm red-bellied one.

Authorities blocked all drains of the reservoir to prevent the piranhas from slipping into canals or rivers, although, they assured, piranhas are not small enough to squeeze through drain holes.

The ministry of environment suspects the piranhas were put in the reservoir intentionally.

The fish were able to survive as it was summer and water temperatures were around 23 degree Celsius as opposed to in winter, when temperatures fall below zero degrees, the ministry explained.