I adopted two African Clawed Frogs about 3 days ago now and I see a fairly big black spot on one of my frogs. I don't know what I did wrong, but I want to correct the issue right away if this isn't normal. The second frog does not appear to have any black spots, but I read it could be a possible water issue? Can anyone follow up and let me know more about specifications on the water, what I need, what I'm doing wrong, etc. while I wait for my how-to book to come in the mail? I want them to have the best possible life and was told they're very easy to care for.