Ponding Water and an EPDM Roof

I was inspecting a large EPDM roof with multiple ponding areas. The owner asked me if the ponding water would hurt his roof. He said, "His brother and he used the same material for his koi pond." Other than the weight and damage to structures and equipment that are in the ponds, I guess you could just add the koi and charge admission.

Call me dense... but this is a joke right? A fish photoshopped into the roof pic?