When I first saw these I thought COOL another way to pimp an aquarium! Then I thought another new toy that uses electricity and water that may not be properly certified and therefore a huge shock hazard to aquarium owners.
A quick search indicates that these have been tested to some standard. See the attched link;
If you buy one of these, look for this mark to be certain that it is built to a safety standard that will protect you and your fish from electricution;