I don't necessarily agree. The concern is very great for the once-supplied wild caught horses, but IME, not nearly so for the captive raised ones. Now I know the pygmy seahorse you are referring to, as I normally go by scientific nomenclature, so the I wasn't entirely familiar with the common name. As far as disease concerns go, the potential is just as high for intraspecifics as it is for interspecifics. Even ones from the same source can become potential problems.