Before becoming a zookeeper, Mr Patel ran a hotel. In Chapter 4, we learn, "An abiding interest in animals led him to the zoo business." So we can infer from this that Mr Patel was not trained as a zookeeper. However, he ran a zoo well and took care of the needs of the animals.
Mr Patel also knew two important concepts or misperceptions common to people visiting the animals in the zoo. The first one being how dangerous it is to give the animals human qualities (anthropomorphism) and second one being that he knew the potentially most dangerous animal in the zoo is man not the lions or the tigers.
His decision to give up the zoo and move to Canada was based not any failure of the zoo itself but on the political situation at the time India.