Have you seen it? So small! This tank is so small it only holds two teaspoons of water. The tank measures 30x24x14mm and there's a baby zebra danio in there if you look close. No filter though...
The chap who designed this tank is also famous for writing on small items such as a grain of rice, poppy seeds and human hair! Good job he has a steady hand.
http://www.youtube.com/watch?feature=player_embedded&v=AG4AvV6wz5Q#at=189
or you can visit his site and see the caravan of camels he placed in the eye of a needle! http://konenko.net/micro-en.htm