What should I do with unexpected koi fry?

Pick it up with a net and place it in a bowl then put adds on the internet or tell your friends, also if nothing works out you have no choice than to give it to the pet store, which would be the last option considering the conditions and how they treat the poor fish. But anyways take it out asap cause when the fish get hungry they will eat it. Gl =) and wow you have that big of a back yard lol.