What is the 4th most popular pet in the world?

It depends on what part of the world we are talking about. It is often and widely regarded that one-eyed snakes top the list at number 1. Number 2 is generally the feline that comes in the form of "Felinus Domesticus" or the highly-sought after Ocelot from the Amazon River Basin. The third most popular fish is the common gold fish (or as it is known in Japan, the Koy). The fourth is the Chinese Giant Panda which - along with the population of China - is vastly increasing in both population and popularity among the world community as suitable house-pets.