I don't see why not... my turtles love to chase and snack on the occasional feeder fish (I rely on food sticks and veggies for the staple diet, though). I'd just make sure the turtles have regular check-ups and ask the vet to de-worm them, as fish can sometimes harbor intestinal parasites. As for the Rubbermaids mentioned here, I second that suggestion - quite cheap, and easy to clean (and remember, as much space as possible). :)
:One other question... :should the turtles have fish living in their tank??? my sister has fish in hers. thanks for the info so far. i have forwarded it to my mom.