I think you have to test the waters.
Questions about the role of zoos in saving endangered or threatened species or preserving diversity in their genomes would be on topic. Questions about how animal behavior studies in zoos help or mislead understanding of animal behavior in the wild would be on topic. Questions about how educational programs affect attitudes to wild animals and wilderness would be on topic.
A question about the different kinds of zoos from roadside petting "zoos" at one end of the spectrum to places like the facility run by the Smithsonian's National Zoo and Conservation Biology Insititue at (or near) the other end of the spectrum would be on topic.
As to a question about the education and training required to be a zoo-keeper, I'm not sure. If such a question about pandas, for example, were connected to panda conservation, it might be.
What I seem to have concluded it that questions about zoos that connect with the animals in their natural habitat are on topic, but questions about zoos as entertainment, even entertainment with a surface gloss of education, are not. (And some official, respectable zoos along the spectrum will have only a self-promoting surface gloss of education.)
My judgment (which is opinionated, but not a prejudice, which means pre-conceived opinion) is that a zoo can justify itself if the benefit to animal species outweighs the harm it inflicts on the animals behind its bars or moats, however that can (or cannot) be measured. I recognize that in some cases, the harm may be minimal, zero, or that some individual animals may benefit from being in a zoo and not the wild. But the bear that still haunts Erik suffered. Longevity by itself is not everything.
One Result of Testing the Waters: the Jan 2019 question about teaching a zoo marine animal to paint was judged to be off topic because it was too heavily slanted towards the entertainment value of sea mammal in an aquarium.