You would be better off releasing that turtle back into the wild and buying a captive bred and raised painted or red-eared slider either at a pet shop, reptile show, or internet. Wild caught animals do not make a good pet for more reasons than I have time to list here, sorry. Look around and do your homework, and then when you are ready, buy a captive born and raised animal, they aren't hard to find nor expensive.
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Jeff Benfer
gartersnakemorph.com