Hello,
We have had a African Bull Frog,(Pixie), for a year, and have tried different substrates. Have learned that the best has turned out to be SAND. It is called Quik Crete play sand. The tank is 2/3 sand and 1/3 water dish, 3 inches deep. We tried gravel, bad, tried bed a beast, coconut, (made a mess of the water). Bubba likes his water dish, which is easy to pull out of the sand and clean, and loves to dig into his sand! Plus when he Poo-Poo's, we don't have to clean his whole cage. We feed him in a separate locking container while cleaning his water dish. Bubba has a fake plant he likes to hide, or sit, on.
Is your frog aggressive? Bubba has bitten Randy 3 times, and when we are around his tank he tries to attack us though the glass.
Bubba is fed a catfish nugget every Wednesday, and then a mouse on Saturday, when we feed our 8 snakes.
Just a suggestion, GO SEAHAWKS!!! Randy and Jan