Hello and welcome. It's tough to see, but I too think he's a Rana (Lithobates) catesbeiana, or American bullfrog.

Mentat has a good start for you. He will eventually need at least a 75 gallon tank at minimal. His water area should have a good filter such as a turtle filter or a filter that is made to handle twice the amount of water that you actually use in the pond area. They are great eaters and will pass wastes as much as they eat. They can jump 3-6 ft easily with one leap as adults, so be sure to have clamps on his screen lid .

Congrats on your new bully! Shortly after he/she absorbs the tail you'll be able to tell his gender.