I wonder how much more social these captive-bred seahorses are when compared to their wild counterparts. In the open water, the young are essentially scattered by the current to some degree (and of course, most are lost to predation....) so I doubt they have nearly as much interaction with other horses as they do in captive growout pens. I just wonder if this increased level of interaction may play a part in the common perception that a single horse in an aquarium appears "lonely." I've heard that if you tape a mirror up to the glass, a seahorse will sometimes try to play with its own reflection.
I was just thinking about this when I saw those two cute babies holding tails in the picture above! ;-)