Each of them weighs around 60kg and stands about 90cm tall, The Saigon Times reported.
According to Saigon Zoo Co. Ltd, the zoo is now fostering 921 animals of 120 species, including some Vietnam’s, and the world’s, rarest species.
Gibbons are social animals which can be found in tropical and subtropical rainforests from northeast India to Indonesia , including the islands of Sumatra, Borneo and Java, and China.
They are strongly territorial, and defend their boundaries with vigorous visual and vocal displays. Their voice can often be heard for distances of up to 1 km.
The species is now threatened or endangered, most importantly from degradation or loss of their forest habitat.