>>This little guy was heading over to the neighbor's pond (he was in our yard). However, our neighbor kills turtles on a regular basis since he's convinced that too many turtles will kill off all his fish.
>>
>>He's missing his hind foot, apparently he had been in trouble once before.
>>

There ya go! If I were in your shoes I'd be keeping him too.
That's an extremely valid reason to keep him as a pet.
I hope everything works out for you.

Let me tell you something that happened with ours in 1998.. he got sick all of a sudden, turned out to be a gouty type of condition he was treated & cured but my vet & all the vets she consulted said then that he must eat very little commercially made food. He should be eating a wide variety of live foods that he'd be eating if he were in the wild.
That's how I got into raising my own bugs. He loves, absolutely LOVES mealworms and lobster roaches. Live fish too..
I feed him a big variety of all sorts of worms, crickets.. I do have to buy some of these foods at the pet store but heck they're small it's not that hard to keep a supply of different bugs.
Since yours is from the wild.. I just wanted you to know about this.
Good luck with him!
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PHRatz