Pick a reason: it leads to a number of serious problems; human food is not healthy for them; they dont need it; they have specialized diets; they can become malnourished or die if fed the wrong foods; their shells cannot maintain proper growth. Keep in mind they also can carry salmonella if you want to touch them also. Just dont. Look at them. Photograph them. Enjoy them. Just resist feeding them. They're fine without you.
Costco had a killer deal on filamentous algea last week. $4.99 a pound.
I'm assuming you have a PhD in turtle nutrition, with a pocketful of dragonfly larvae and filamentous algae, ready to shepherd the little heathens towards optimal health. Anyway, people usually feed wild animals to get a better look, but the turtles at this location regularly come within 5 feet of visitors, so no need.
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