Rarest animals to be seen in zoos or aquaria?

I was about correct the Tas devil, squatter pigeon and maguari stork, but I see that all this has been already done...
Unfortunately no black-necked stork (my favourite stork species) left in Europe.
Somebody mentioned the very endangered Spoon-billed Sandpiper in Slimbridge? Are there more of this species in non-european zoos? London keep many caecilians that muts be unique or almost unique, too... And don't forget about cetaceans (Amazon river dolphin at Duisburg, last Commerson's dolphins and pygmy orca in a place in Japan which name I don't remember...)

 

Also concerning storks- does anyone know whether the lone individual at the Gladys Porter Zoo is a greater adjutant or a marabou? I only saw it with its back turned, hence my confusion. There wasn't a sign and it was kind of in between the African and Asian sections of the zoo. Gladys Porter has had greater adjutant in recent years- I think even to 2013, but I haven't seen anything about it that is current.

 

do you have a photo? Even turned back and hence unable to see the vivid yellowish orange of the neck of greater adjutant (pink in marabou stork), the colour of wings could tell them appart.
Regarding rarest animals in zoos, I remember a sing in the tank of SeaWorld San Diego that contained trouts of the species Oncorhynchus aguabonita, regarding "This is the only zoo in the world to have this species", or something similar.
And I think that another good candidate for rarest species in zoo, is the numbat. How many Australian zoos keep it? I'm sure that none non-australian zoo keep it...

 

Thanks- I figured that was the case (I know for a fact it wasn't a lesser adjutant) but I figured I'd get someone else's opinion.

I do- I'll post it when I get home and link it to this thread. I am unfamiliar with the greater adjutant (and to be fair, I know little about the marabou stork either), so your assistance for identifying it would be much appreciated.

 

I looked over some photos and am now even more certain that TLD is correct in saying that it's a marabou stork. Here's the photo:
Leptoptilos ID | ZooChat

 

Sorry, but finally it's an african marabou stork, very common in worldwide zoos... not a greater nor lesser adjutant, both very rare in zoos.

 

Unless something has changed recently, Gladys Porter does hold a single marabou stork. This is most likely the animal that you saw.

 

There are no captive Spoon-billed Sandpiper aside from Slimbridge unless Moscow has any. Current status is that there were 2 hatched (dns) this year - the first captive breeding anywhere. Headstarting of first clutches taken on the breeding grounds and then released while the wild birds re-lay seems to have had some success, so the actual rearing in captivity seems to be doable.

 

https://www.facebook.com/video.php?v=834583293244797

 

I assume these are pupfishes of some sort, right? London Zoo keeps more pupfish species than any other european zoo, and many of them are extint in the wild. The same for Partula snails. Unfortunately, when I was here (2006) they only had one species in public display (Cyprinodon longidorsalis).

 

Monkey-eating eagle (Planckendael), Tasmanian devil (Copenhague), sumatran rhino (Bronx), rockfowl (Bronx), slender-horned gazelle (Planckendael, nowadays also in Landau), red shanked douc langur (Koln, nowadays also in Chelbyà, blue coua (Koln), rufous elephant shrew (Koln, nowadays only in Antwerp and Rotterdam), central american bushmaster (Koln), Northern-Vietnamese threestriped box turtle (Munster), Pacific hornero, Sumatran trogon, solitary tinamu, lance-tailed manakin, giant pitta, Sumatran leafbird, dark-throated oriole and 12-wired BOP (all Walsrode), red-billed oxpecker (Hamburg), eastern lowland gorilla (Antwerp), black-cheeked waxbill (Hamburg), trumpet manicode, soda ciclid, piraputanga, Sri Lanka wood owl, blue-winged pitta, Japanese serow (also in Magdeburg), vampire bat, metallic starling, James flamingo, kagu (also Wuppertal and Walsrode), Javan leopard (also Tierpark), speckle-fronted weaver (also one other institution unknown to me), Asian pied starling (all Zoo Berlin), Mexican rough-footed turtle, tropical kingbird, black-chinned fruit dove, chaco peccary (nowadays also Wuppertal and Planckendael), bay-headed tanager, long-nosed snake, arrow-marked babler and many others (Tierpark Berlin), Harpy (Wuppertal, also Nurnberg and Tierpark), eastern quoll, flame-faced tanager, Malayan swamphen, Chinese pangolin, baikal seal (also seen in Burgers), ring-necked spotted cobra (also in Koln?) (all Leipzig), greater prairie chicken (Luisenpark), North Island kaka, Uganda red billed firefinch (Wilhelma), yellow-backed duiker (Wuppertal), Abruzzen chamois (Hellabrun), screaming piha (Burgers and Hellabrunn), rocky mountains bighorn, ashy tailorbird, ringtailed cat, lemon bellied white-eye, yellow gosbeak, murray river turtle, mountain toad, little kitfox, golden-fronted leafbird and Cape hartebeest (all Burgers Zoo), Peruvian pygmee owl, Sudan brown warbler, calfbird, plate-billed mountain tucan (also Berlin i think), Pompadour cotinga (also Wuppertal), Mindanao rufous hornbill, bare-throated fruit crow, Angola peachfaced lovebird, Jardine's parrot, long wattled umbrellabird (also Walsrode) (all NOP), blue manakin, shining honeycreeper, berryline humingbird, white-throated bee-eater, rufous brested hermit, golden-headed manakin, tropical house wren, black-footed cat, bairdt's tapir, Indian leopard, Pompadour cotinga, etc (all Wuppertal), masked palm civet (Dortmund), Orinocco delphin (Duisburg), Chinese ferret-badger, helmeted friarbird, Zanzibar bishop, Indochina featherback (Prague), Klipspringer (also seen in Artis and Rotterdam) and short-beaked echidna (Frankfurt), common wombat (also Duisburg and hannover), chestnut munia (also Antwerp and Plzen), crestless curassow (also Walsrode), (all Planckendael)... this list goes a whole end. All based on visits. Sadly many of these species are vanishing from european collections.Some are doing well and are slowly expanding.