The jewel tanks in the "Mekong River" zone - these zones don't make much sense any more as the geographic theming has largely been dropped in favour of two broad categories of Africa and Asia-Pacific.
These tanks now house threatened small Southeast Asian freshwater fish:
Tank 1: Bintan Licorice Gourami (Parosphromenus bintan), Chilli Rasbora (Borara brigittae)
Tank 2: Bigspot Barb (Barbodes dunckeri), Harlequin Rasbora (Trigonostigma heteromorpha)
Tank 3: Tiger Hillstream Loach (Sewellia lineolata), Emerald Dwarf Danio (Danio erythromicron), Dwarf Botia (Ambastaia sidthimunki)
Tank 4: Red Rainbowfish (Glossolepis incisus), Boeseman's Rainbowfish (Melanotaenia boesemani)