Ecosystem in a bag of holding

[Ravens_cry]

That... I'd like to see.

Also, you're gonna need a Decanter of Endless Water in there too, well, either that or lots of Create Water spells. Using Genesis to increase the size of the demi-plane helps a lot as well.

Unless you keep the bag of holding the whole time, once you have the initial water supply, (if done right) you only need to add more water at very irregular intervals.
http://en.wikipedia.org/wiki/Closed_ecological_system