This is the current species list, but it was probably different when the photo was taken:
Upside down jellyfish
Atlantic horseshoe crab
Mudflats fiddler crab
West African fiddler crab
Blue-legged hermit crab
Waby turban
Largescale four-eyed fish
Liberty molly
Mangrove molly
Atlantic blue tang surgeonfish
Mangrove rivulus
Yucatan gambusia
The whole Mangrove is amazing! It also has a giant enclosure for Manatees and hundreds of Central American cichlids, as well as free-roaming birds like Violaceous euphonia, Red-legged honeycreeper, Blue ground dove and Crested bobwhite. And over 20 butterfly species and a few reptiles
Burgers' Zoo is definitely a must-visit in Europe. It also has a huge aquarium, a giant tropical greenhouse (the bush) with over 30 free-roaming birds, and a desert house with some very rare free-roaming animals (such as the Yellow grosbeak, which isn't held in any other European zoo)
Personally I'd go for different zoos when visiting the Netherlands. Do what you want, of course. But I'd say Beekse Bergen (giant safari park with interesting viewing points) and Wildlands (Zoo with beautiful theming while still having high-quality exhibits) are more worth visiting than Artis or Blijdorp. GaiaZOO is also really high up there in terms of zoo quality, but it's really on the edge of the country and often overlooked
