One American or Fowler's Toad would do well in that setup. My toads soak in large bodies of water so they wouldn't mind it. I think it's called an oak toad that would get like 1-1.5 inches and you could have a lot of toads in that setup. Maybe a Tomato Frog would be a possibility they are very similar to a toad. You could have a pair in this setup.

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