The Wild Water Buffalo, Bubalus arnee is endemic population found naturally in Koshitappu Wildlife Reserve. In 1976, its population was around 63 individuals. In the same year Koshitappu was announced as Wildlife Reserve. Since then the trend of Arnee population is increasing each year. Now its total population is around 500 individuals.
In 2018, 12 Arnee 10 males and 2 females were translocated to Chitwan National Park. Objective of translocation is to conserve gene pool and to control inbreeding. Translocated population of Arnee is also increasing in Chitwan National Park.
An aged water buffalo was found eye damage in Jamuva, Saptari. A tranquilizer expert team was called for treatment from Chitwan National Park. Water buffalo was tranquilized and made medication. Then, released in the reserve.