50 gallon tank is recommended for one large adult frog (they can get big 6-8 inches is average sometimes bigger). Be sure to house individually, can be territorially and/or cannibalistic, especially males! Mostly water, with a small land area (1/3 land 3/4 water is a good ratio). Be sure the water is fairly deep, at least 6inches and be sure it is filtered. But in regards to filtration use a filter that creates little current b/c bullfrogs inhabit still waters. Temperature range of around 78-82 during the day, with a slight drop at night. For substrate, be sure it is larger than the frog can swallow. Big frog = big mouth. Provide a photo period, and keep moderate humidity (60-70%). A very very hardy species with a large appetite. I would recommend chopped night crawlers, large crickets and roaches when the frog is smaller. And feed large night crawlers, large roaches, grasshoppers, locust and any other large invertebrates you can get your hands on (just be sure they are pesticide free). Enjoy and good luck!