actually a male southern painted might do okay in a 29 gallon... granted i am saying that not having researched turtles in a while.. i LOVE turtles. i think they are adorable.
i know turtles need approximately 10 gallons per inch (for a full grown turtle, of course), and male southern painteds stay tiny (females get a bit larger, i believe)...
www.turtleforum.com - GREAT site.
dino is right though, they are VERY messy!
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
make sure to get us pictures if you do decide to get a turtle.
edited to add: here's a care sheet for southern painteds - looks like 29 gallons may be a bit small, though i think you could do it with a strong filter, maybe...
Care Sheet - Southern Painted