Visited another zoo yesterday. It was one of the few large* German zoos that I haven't seen yet. Now I'm lacking almost only those zoos in the far South Western regions of the country, this is an area that's pretty far away for me and therefore I haven't been there yet.
* As a large zoo I consider those with a majority of the big ticket animal groups (big cats, bears, great apes, seals, pachyderms,...)
Speaking about medium sized and small zoos, I still have A LOT to see only here in Germany and it's probably impossible to see them all (should be a few hundred officially registered institutions that count as a zoo), so I concentrate on the larger ones for now. And honestly those small roadside kind of zoos/petting zoos are not the most interesting ones for me. I rather visit medium sized or large zoos in other countrys then.