So it is an order of evolutionarily distinct mammals comprised of one family in which all of the extant species are either vulnerable , endangered or critically endangered due to habitat destruction and hugely unsustainable levels of poaching for the Chinese traditional medicine trade. It strikes me as a group of mammals which given the dire situation they are facing in the wild are ideal candidates for ex-situ captive breeding programes in zoos both Asian and Western. It could be argued that perhaps pangolins are even in a greater need of these kind of programes than megafauna like rhinos , tigers, great apes, elephants etc. Granted , there are difficulties in keeping them alive in captivity but historic examples of conservation interventions show that with decent research undertaken into understanding the ecological requirements of a species the overwhelmingly majority of animals can be maintained and bred in captivity. Recent research has been performed into filling in the gaps of knowledge regarding how to do this for pangolins in captivity so things are slowly improving and of course a period of trial and error has taken place and will do in the future. So in your opinion what are the main barriers to establishing pangolins ex-situ in zoos ?