Handsome little guy!
I haven't kept this species, but he's probably similar in care requirements to other Ambystoma. Keep him cool (preferably 50-70 F) and moist, give him plenty of hiding spots and a substrate he can burrow in, and give him a variety of live prey (crickets, waxworms, mealworms, and earthworms are all fine). One or two would be OK in a 10 gallon, though a 20 gallon long would be better.
Please don't release him; once an animal has been in captivity it should never be returned to the wild. There is too much risk of spreading pathogens or parasites to the wild populations.