With the proper research and dedication...seahorses are some of the more entertaining as well as fascinating life in the hobby.
The wild caught and captive bred debate is a debate...I leave it be, don't offer opinions either way.
If you decide on seahorses, from my own experience, this is what I have learned.
They don't really care about a tall tank or not. If you intend on breeding them, then you need to be concerned as they mate while swimming upwards.
Be prepared to have a constant supply of live brine with vitamins. Even though captive bred are more apt to eat frozen mysid, some still are picky. A five gallon trank with a foam air filter is sufficient for this purpose. I keep mine right below the tank. Either or, both types will have a specific food they will eat. Some will eat both, and some will eat just one.
Either way with the food, vitiman enrich it often.
They don't like nitrates. They have to have good water.
Being the situation I have going right now, I have one seahorse in with the damsels. The damsels are keeping the tank going until my basement sump is completed, hopefully this week. The other tank is already finished (prior seahorse tank), but will now become a reef. So for now, the seahorse stays with the damsels. I feed the damsels at one end of the tank, and the seahorse at the other end. I pre thaw the frozen mysis in a small glass cup of tank water. I poor little bits in at a time. For the one horse, 1 cube of frozen last 2 days, about 4 feedings, if this gives you any indication of how little the bits are. By the time the damsels realize what is going on the other end of the tank, he has already consumed several shrimp. Has been working out great for the past 4 weeks or so.
I have had this guy for over a year now. Cool fish.
Anyways, best kept in a species only tank with slower water currents.
If you have rock in the tank, make sure it is secure. Seahorses move slow, so they are prone to rock cave-ins and such. I lost one of my kudas to a pincushion urchin caused rock collapse. Crushed his upper extremities between the rock and the glass of the tank.
They dont like air bubbles. Injested air can lead to bouyancy problems. Older and younger seahorses will confuse the bubbles with food, and consume it. They are sometimes not the brightess bulb in the light bulb aisle.
If you keep the little tiny dwarfs, which are cool too, plan on spending a ton of time with the water. They pretty much are limited to extremely small types of food, baby brine shrimp/naupuli. The water to food to time ratios will wreak havoc with your bio-filtration. Smalled tank here, the better.
Give the proper research, and committment, seahorse keeping is rather enjoyable. Once I decide on what type of tank will be next for the species only, my little guy will have plenty more company. Probably will be a 35-45 hex tank piggy backed off the reef for the prestine water quality.
Good luck.