Seahorses don't have a true stomach, only a short tube so they have almost no capacity to store food. If you ever dove with them, you will see them eat or try to eat something all day. They eat very little at each meal because they can't dijest very much at all. All of that extra food they are eating at one meal will not be dijested.
Like mandarins, they should be fed as often as possable. They will of course live on a meal twice a day but less food, more times a day is much more natural for them.
I have collected them numerous times here in NY and raised them to adulthood.
I even invented and patented a feeder for them that would feed them live brine shrimp all day. We no longer feed live brine shrimp so I don't sell the thing any more. Mysis is much better for them.
http://www.breedersregistry.org/Articles/v4_i3_paul_b/paul_b.htm