Although the building is to nowhere near the same scale, it should be noted that the Monsoon Forest house at Chester has several free-roaming species of reptile, and that the Butterfly House has a large population of free-roaming Trinidad Stream Frog.
I see your argument for Galapagos Giant Tortoise and note that citing the presence of pure individuals as a particular positive
sounds good until you reflect that these comprise a single male of one taxon and a single female of another, and that the animals produced by these successful breedings are therefore *not* pure individuals.
Moreover, I raise your "
first zoo to breed Galapagos Giant Tortoise in Europe" argument with a corresponding "
first and only zoo to breed Tuatara outside New Zealand full stop" argument

Chester has more than its fair share of rarities when it comes to ectotherms, both in terms of onshow taxa and species kept offshow for reintroduction breeding programmes - the latter include Montseny Brook Salamander (Chester being the only place outside Spain to keep or breed this extremely rare European native species) and Bermuda Skink. When I marshall my thoughts for a full breakdown of the merits of Chester in this category I will return to this point!
I don't recall seeing any exhibits of this nature - do you have any photographs?
In all honesty, I think that has
approximately as much bearing on the matter as (for instance) trying to claim that Walsrode would have a shot in this category because of the massive population of frogs and newts I have observed within the grounds of the zoo
If this is true, then the aquarium exhibits highlighted by lintworm would be exempt from consideration - although I hadn't heard this was the case, I had also missed the news that the "Research Station" had opened, so would appreciate further clarification on this point.
---
As regards the run-down provided by
@lintworm of the new display which recently opened up within the Exotarium, it *
does* sound pretty good - although I'll note that it sounds like he is citing the promotional material rather than personal experience (for instance, using photographs from the zoo website) and that the "
unique set-up" seems to be a slightly-more regimented form of the Tripa Research Station area within Monsoon Forest at Chester, which displays various invertebrates, fish and herps in an imitation research setting complete with hand-written notes and journals.... so not really unique!
---
I'd be interested to hear the arguments from
@OkapiJohn and
@Haasje regarding why they view Chester as being worthy of only a single point; I will be providing a detailed breakdown of the merits of the collection later tonight when I have a bit more time and mental energy to marshall my thoughts, but even on a surface level I think that giving Zurich 4 points is excessively gilding the lily and being highly-unfair to Chester!
----
I'd assert that
none of the exhibits scattered around Zurich outside the Exotarium which
@lintworm highlighted exceed the quality demonstrated by Chester in this category - and that several fail to reach it.
For instance, you can't exactly call the tortoise exhibits in Lewa and the Elephant House - cited by him as particular highlights of the non-Exotarium offerings - anything particularly remarkable!
But again, I'll be putting my money where my mouth is anon.