Just a few comments that I've been answering via PM/email:
My personal experience with H. comes, and this corresponds with what I've heard from others with them - they appear to be happiest at ~76-78F. I wouldn't keep them at temps >78F (at least not for long term) as I do believe that vibrio and other bacterial/viral infections are more deadly at higher temperatures. They do fine at lower temps (I've kept them as low as 68F for short periods) but they become quite sluggish at temps lower than 75F.
In general, captive bred seahorses are more social than wild caught. Most captive bred seahorses are raised in fairly close quarters whereas wild caught seahorses are generally more solitary/territorial. I can't remember the exact figures, but I believe that in the wild, each pair of seahorses will have a territory of multiple square meters. In comparison, captive bred, tank raised (I don't know about net pen raised as I have no direct experience) seahorses are kept at much higher stocking densities.
I keep small juveniles at roughly 4-6/gallon, large juveniles at 3-5/gallon, sub-adults at 2-4/gallon and young adults at 1-2/gallon. My adult stocking levels are also higher (roughly 1-2 gallons/'horse) than most people recommend, mostly because I've found that even when put in a quite large tank, with some exceptions, the captive bred 'horses tend to congregate together.
Additionally, groups of 'horses seem to eat better - I find that solitary, or isolated pairs of 'horses do not have the same hunting behavior as groups of 'horses. I think that there's a certain amount of competition instinct. I've never had any wild caught 'horses, so I don't know if this is something that is more prevalent with captive bred.
I, personally, have not had very good luck training H. comes to use a feeding dish. However, a number of people that have bought them from me have reported good success. On the other hand, I don't have any tanks with less than 12 'horses in them, which makes it difficult to get each and every one to come to the feeding dish..
Theoretically, I feed the juveniles 3-4x/day, sub-adults 2-3x/day and adults 1x/day. In practice, the adults get fed at least 2x/day because when they see me feeding everyone else, they line up and beg.....
I feed exclusively Hikari frozen mysis, I enrich 1 feeding, every other day, with Naturose, Vitamin C and Beta Glucane.
Lastly, I've found that the H. comes prefer higher flow than my H. reidi. I generally try for 30x tank volume in flow. It is *very* important the the flow is not chaotic and that there are areas of lower flow for them to rest in.