I love miniatures. This guy, Анатолий Коненко, makes miniatures for fun and profit. He's done a lot of other stuff, including a tiny book (1 mm square), a tiny mousetrap (6 mm x 3 mm), a grasshopper-sized violin, and a caravan of camels that fit through the eye of a needle. The first two as well as this aquarium are all Guinness world records.
The aquarium holds 10 mL of water and actually houses three itty bitty baby zebrafish (Danio rario), which Анатолий places into the water using a teeny net that, presumably, he also made. Here's a video.