This list is composed of the species I actually saw on my visit to Sydney Zoo on 24/04/2021. @Simon Hampel has confirmed that the Asian Small-clawed Otter were present, but I personally didn't see them so I have excluded them from my list. For some species I have included counts based on what I saw on the day I visited, so these numbers may not reflect the actual population held by the zoo.
Sydney Zoo Species List April 2021
Mammals (35):
Spotted-tailed Quoll (Dasyurus maculatus) 1
Tasmanian Devil (Sarcophilus harrisii) 2
Greater Bilby (Macrotis lagotis) 1
Koala (Phascolarctos cinereus)
Common Wombat (Vombatus ursinus) 2
Long-nosed Potoroo (Potorous tridactylus) 1
Tammar Wallaby (Macropus eugenii) 2
Western Grey Kangaroo (Macropus fuliginosus)
Yellow-footed Rock Wallaby (Petrogale xanthopus)
Swamp Wallaby (Wallabia bicolor) 3
Common Ringtail Possum (Pseudocheirus peregrinus) 2
Yellow-bellied Glider (Petaurus australis) 1
Feathertail Glider (Acrobates pygmaeus)
Common Brushtail Possum (Trichosurus vulpecula) 1
Ghost Bat (Macroderma gigas)
Spinifex Hopping Mouse (Notomys alexis) 3
Asian Elephant (Elephas maximus) 2.1
Plains Zebra (Equus quagga) 3
Dromedary (Camelus dromedarius) 4
Giraffe (Giraffa camelopardalis) 2
Domestic Sheep (Ovis aries) 1
Domestic Goat (Capra aegagrus hircus) 2
Tufted Capuchin (Sapajus (Cebus) apella) 12 (13 total according to the keeper talk)
Hamadryas Baboon (Papio hamadryas)
Sumatran Orangutan (Pongo abelii) 1.2
Common Chimpanzee (Pan troglodytes) 9
African Lion (Panthera leo) 4.0
Sumatran Tiger (Panthera tigris sumatrae) 1.0
Cheetah (Acinonyx jubatus) 2.0
Dingo (Canis lupus dingo) 1
African Wild Dog (Lycaon pictus) 4
Spotted Hyena (Crocuta crocuta) 3.0
Meerkat (Suricata suricatta) 15
Red Panda (Ailurus fulgens fulgens) 2.0
Capybara (Hydrochoerus hydrochaeris) 1.1.6
Birds (4):
Emu (Dromaius novaehollandiae) 1
Southern Cassowary (Casuarius casuarius) 1
Common Ostrich (Struthio camelus) 1.0
Little Penguin (Eudyptula minor)
Reptiles (26):
Saltwater Crocodile (Crocodylus porosus) 1
Lace Monitor (Varanus varius) 2
Perentie (Varanus giganteus) 1
Merten’s Water Monitor (Varanus mertensi) 1
Heath Monitor (Varanus rosenbergi) 2
Black-headed Monitor (Varanus tristis) 1
Eastern Water Dragon (Intellagama lesueurii) 1
Burns’ Dragon (Amphibolurus burnsi) 2
Central Netted Dragon (Ctenophorus nuchalis) 1
Frill-necked Lizard (Chlamydosaurus kingii) 2
Boyd’s Forest Dragon (Lophosaurus boydii) 2
Shingleback (Tiliqua rugosa) 1
Gidgee Skink (Egernia stokesii) 2
Northern Spiny-tailed Gecko (Strophurus ciliaris) 1
Centralian Knob-tailed Gecko (Nephrurus amyae) 1
Scrub Python (Morelia amethistina) 1
Centralian Carpet Python (Morelia bredli) 1
Diamond Python (Morelia spilota spilota) 1
Rough-scaled Python (Morelia carinata) 1
Green Tree Python (Morelia viridis) 2
Broad-headed Snake (Hoplocephalus bungaroides) 1
Common Death Adder (Acanthophis antarcticus) 1
Tiger Snake (Notechis scutatus) 1
Red-bellied Blake Snake (Pseudechis porphyriacus) 1
Eastern Brown Snake (Pseudonaja textilis) 1
Inland Taipan (Oxyuranus microlepidotus) 1
Amphibians (3):
Green Tree Frog (Litoria caerulea)
Magnificent Tree Frog (Litoria splendida)
Green and Gold Bell Frog (Litoria aurea)
Fish (24):
Murray Cod (Maccullochella peelii)
Seven Spot Archerfish (Toxotes chatareus)
Indo-Pacific Tarpon (Megalops cyprinoides)
Giant Glassfish (Parambassis gulliveri)
Gulf Saratoga (Scleropages jardinii)
Lesser Salmon Catfish (Neoarius graeffei)
Silver Batfish (Monodactylus argenteus)
Crimson-spotted Rainbowfish (Melanotaenia duboulayi)
Boeseman’s Rainbowfish (Melanotaenia boesemani)
Black-banded Rainbowfish (Melanotaenia nigrans)
Banded Rainbowfish (Melanotaenia trifasciata)
Neon Rainbowfish (Melanotaenia praecox)
Salmon Red Rainbowfish (Glossolepis incisus)
Australian Lungfish (Neoceratodus forsteri)
Eastern Blue-eye (Pseudomugil signifer)
Northern Trout Gudgeon (Mogurnda mogurnda)
Empire Gudgeon (Hypseleotris compressa)
Longfin Eel (Anguilla reinhardtii)
Golden Perch (Macquaria ambigua)
Australian Bass (Macquaria novemaculeata)
Bull Shark (Carcharhinis leucas) 1
Jade Perch (Scortum barcoo)
Milkfish (Chanos chanos)
Yellow-eye Mullet (Aldrichetta forsteri)
Invertebrates (5):
Smooth Yabby (Cherax destructor)
Spiny Katydid (Phricta spinosa)
Goliath Stick Insect (Eurycnema goliath)
Spiny Leaf Insect (Extatosoma tiaratum)
Flinders Range Scorpion (Urodacus elongatus)
Total: 97 (98 including otter)
Sydney Zoo Species List April 2021
Mammals (35):
Spotted-tailed Quoll (Dasyurus maculatus) 1
Tasmanian Devil (Sarcophilus harrisii) 2
Greater Bilby (Macrotis lagotis) 1
Koala (Phascolarctos cinereus)
Common Wombat (Vombatus ursinus) 2
Long-nosed Potoroo (Potorous tridactylus) 1
Tammar Wallaby (Macropus eugenii) 2
Western Grey Kangaroo (Macropus fuliginosus)
Yellow-footed Rock Wallaby (Petrogale xanthopus)
Swamp Wallaby (Wallabia bicolor) 3
Common Ringtail Possum (Pseudocheirus peregrinus) 2
Yellow-bellied Glider (Petaurus australis) 1
Feathertail Glider (Acrobates pygmaeus)
Common Brushtail Possum (Trichosurus vulpecula) 1
Ghost Bat (Macroderma gigas)
Spinifex Hopping Mouse (Notomys alexis) 3
Asian Elephant (Elephas maximus) 2.1
Plains Zebra (Equus quagga) 3
Dromedary (Camelus dromedarius) 4
Giraffe (Giraffa camelopardalis) 2
Domestic Sheep (Ovis aries) 1
Domestic Goat (Capra aegagrus hircus) 2
Tufted Capuchin (Sapajus (Cebus) apella) 12 (13 total according to the keeper talk)
Hamadryas Baboon (Papio hamadryas)
Sumatran Orangutan (Pongo abelii) 1.2
Common Chimpanzee (Pan troglodytes) 9
African Lion (Panthera leo) 4.0
Sumatran Tiger (Panthera tigris sumatrae) 1.0
Cheetah (Acinonyx jubatus) 2.0
Dingo (Canis lupus dingo) 1
African Wild Dog (Lycaon pictus) 4
Spotted Hyena (Crocuta crocuta) 3.0
Meerkat (Suricata suricatta) 15
Red Panda (Ailurus fulgens fulgens) 2.0
Capybara (Hydrochoerus hydrochaeris) 1.1.6
Birds (4):
Emu (Dromaius novaehollandiae) 1
Southern Cassowary (Casuarius casuarius) 1
Common Ostrich (Struthio camelus) 1.0
Little Penguin (Eudyptula minor)
Reptiles (26):
Saltwater Crocodile (Crocodylus porosus) 1
Lace Monitor (Varanus varius) 2
Perentie (Varanus giganteus) 1
Merten’s Water Monitor (Varanus mertensi) 1
Heath Monitor (Varanus rosenbergi) 2
Black-headed Monitor (Varanus tristis) 1
Eastern Water Dragon (Intellagama lesueurii) 1
Burns’ Dragon (Amphibolurus burnsi) 2
Central Netted Dragon (Ctenophorus nuchalis) 1
Frill-necked Lizard (Chlamydosaurus kingii) 2
Boyd’s Forest Dragon (Lophosaurus boydii) 2
Shingleback (Tiliqua rugosa) 1
Gidgee Skink (Egernia stokesii) 2
Northern Spiny-tailed Gecko (Strophurus ciliaris) 1
Centralian Knob-tailed Gecko (Nephrurus amyae) 1
Scrub Python (Morelia amethistina) 1
Centralian Carpet Python (Morelia bredli) 1
Diamond Python (Morelia spilota spilota) 1
Rough-scaled Python (Morelia carinata) 1
Green Tree Python (Morelia viridis) 2
Broad-headed Snake (Hoplocephalus bungaroides) 1
Common Death Adder (Acanthophis antarcticus) 1
Tiger Snake (Notechis scutatus) 1
Red-bellied Blake Snake (Pseudechis porphyriacus) 1
Eastern Brown Snake (Pseudonaja textilis) 1
Inland Taipan (Oxyuranus microlepidotus) 1
Amphibians (3):
Green Tree Frog (Litoria caerulea)
Magnificent Tree Frog (Litoria splendida)
Green and Gold Bell Frog (Litoria aurea)
Fish (24):
Murray Cod (Maccullochella peelii)
Seven Spot Archerfish (Toxotes chatareus)
Indo-Pacific Tarpon (Megalops cyprinoides)
Giant Glassfish (Parambassis gulliveri)
Gulf Saratoga (Scleropages jardinii)
Lesser Salmon Catfish (Neoarius graeffei)
Silver Batfish (Monodactylus argenteus)
Crimson-spotted Rainbowfish (Melanotaenia duboulayi)
Boeseman’s Rainbowfish (Melanotaenia boesemani)
Black-banded Rainbowfish (Melanotaenia nigrans)
Banded Rainbowfish (Melanotaenia trifasciata)
Neon Rainbowfish (Melanotaenia praecox)
Salmon Red Rainbowfish (Glossolepis incisus)
Australian Lungfish (Neoceratodus forsteri)
Eastern Blue-eye (Pseudomugil signifer)
Northern Trout Gudgeon (Mogurnda mogurnda)
Empire Gudgeon (Hypseleotris compressa)
Longfin Eel (Anguilla reinhardtii)
Golden Perch (Macquaria ambigua)
Australian Bass (Macquaria novemaculeata)
Bull Shark (Carcharhinis leucas) 1
Jade Perch (Scortum barcoo)
Milkfish (Chanos chanos)
Yellow-eye Mullet (Aldrichetta forsteri)
Invertebrates (5):
Smooth Yabby (Cherax destructor)
Spiny Katydid (Phricta spinosa)
Goliath Stick Insect (Eurycnema goliath)
Spiny Leaf Insect (Extatosoma tiaratum)
Flinders Range Scorpion (Urodacus elongatus)
Total: 97 (98 including otter)