That's an American Bullfrog (Rana Catesbiana) for sure. They make great pets, and are very fun to keep. I suggest a 20-30 gallon for a juvenile bullfrog, and at the minimum, a 55 gallon for an adult, 120 gallon max (For example, for a 6-8 inch bullfrog an 100-120 gallon, and for a 4-5 inch, a 55-90 gallon).
I recommend feeding it a diet compromised of crickets and earthworms, dusting the crickets with a calcium + Vitamin D3 mix every other feeding, which should be every other day. Dust the crickets with a multi-vitamin mix once a week, and I recommend feeding them earthworms (from a pesticide/additive free source) every other feeding. They are very nutritious, and easy to digest. Feeding crickets about the size of the space in between its eyes is a good measure. I only recommend 1-4 inch earthworms for a froglet like yours. As for mealworms, pinky mice, and feeder goldfish, I don't recommend any of the three mentioned. Mealworms, because they are so hard to digest and have very little nutritional value. Pinky mice because they are high in fat and hard to digest, too. As for feeder fish, I really dislike goldfish because of their high parasite rate. Guppies and minnows are OK as long as they come from a parasite-free source, and you know, adamantly, that they do.
You're also going to need a good filter, such as a Fluval U1-4 underwater filter, or a canister filter. These guys produce a lot of bio-waste, and eat a LOT.
I suggest making a land-water setup, mainly compromised of water. For my juvenile Bullfrog (Rana Catesbiana) and juvenile Green frog (Rana Clamitans), their tanks are about 80% compromised of water, with a small, dry land section they can crawl up on. For the water section, I strongly suggest either fake water reeds, fake/live lily pads, and duckweed, as these frogs will dive for cover if scared. As for the level of water, I use 4 inches for juvenile bullfrog. For yours, due to its size, you may want to try 2-3 inches at the most. As for substrate, I use medium sized pond stones, too large to be ingested. I would lay them down in one layer on the water section, then slowly ramp them up to form the land. You can help make the land with driftwood, or simply use a divider. However, make sure the frog has somewhere easily accessible and dry to climb onto, and lots of cover.
As for bio-type, a swamp or edge-of-a-pond bio-type is perfect for an American Bullfrog. If you do use moss, I STRONGLY recommend you keep it away from the eating area, as if ingested it can cause a prolapse or impaction. I also recommend you use an aquarium background for the back and sides of the tank to make the frog feel more secure. Lids are a must, as these guys can jump far, high, and fast.
I think I've covered most of the major points, and I can give you some examples of American Bullfrog setups.
Have any more questions, just ask. Oh, and Welcome to the Frog Forum![]()