Finishing a Fortress

[LoyalPaladin]

Not that i know of, but i'd just throw random organic material to them just in case.

Like Yuan-Ti!

[unseenmage]

...

On a more on topic note, do I need to feed Gelatinous Cubes?

To my knowledge every living thing needs to eat, sleep, and breathe. Even oozes.
Something I remember reading once about monsters starting with basic human needs and exceptions being listed in their descriptions or the type rules. Beyond that they need what we need, just in different doses depending on the creature (elves less "sleep", horses more food, etc).

[Ferronach]

MM1 says that: "Oozes are amorphous creatures that live only to eat. they inhabit underground areas throughout the world, scouring caverns, ruins and dungeons in search of organic matter - living or dead." -(MM1 p. 201 WOTC)

As far as I know, any organic matter will work... you could feed them in place of having a compost heap/garbage dump, you could throw the bodies of your fallen foes to them... heck you could probably even use the moat as a latrine. The ooze would simply dissolve anything organic and break it down to its basic elements and then absorb them.