How funny it is to be on a site for the first time and find a link to pictures of my tank.
Before I enter into this whole debate
, I would first like to take time to anwser the question that was purposed.
Seahorses are very delicate and should not be attempted by someone without adaquete research. It is recommended that you have at least one year of salt water expierence before keeping these creatures. That being said a seahorse was my first fish, and he has been with me for three years. It can be done. It will take work. It will take a ton of research.
Since seahorses like to swim vertically you will need to setup a taller tank for them. The tank size should be three times the height of the seahorse, for starters. Different spieces of seahorses will grow to be different heights so it will depend on the spieces you decide.
While wild caught speciments can sometimes be less expensive intially, you will save time and money in the long run by purchasing a captive breed seahorse. A CB seahorse is more resistant to pathogens and woll more readily accept frozen food, such as mysis; while WC speciments can be trained to accept frozen food, some never make the switch and need to be fed live food, such as ghost shrimp, on a daily basis. Keep in mind if you purchase a WC seahorse you will need to have a feeder tank running at all times or make daily trips to your LFS for food.
Purchasing a captive bred seahorse also stops the depletion of the cretures in the wild.CB seahorses are not at all hard to find here in the U.S.
While liverock or livesand is not essentail for survival, it will help with filtration and leave a place to put those seahorse friendly corals. I recommend one pound of liverock per gallon, and a deep sand bed of around 5 inches. Others may disagree, but in my expierence this has worked great for me. If you do not go with these you will need to add additional filtration to your tank.
Added filtration is always a good idea. A simple HOB filter will work, biowheels are also good, as well as cannisters. I believe that a UV sterilizer should be required, especially if you are going to be feeding live food. These units will help not only with pathogens but also with algaes.
Here are the basic tank specifications. You should make sure your tank is fully cycled matured with theses readings before adding a seahorse.
pH - 8.0 to 8.3
Specific gravity - 1.021 to 1.024
Ammonia - 0
Nitrite - 0
Nitrate - <20 ppm
Seahorse do not require intense lighting. If you plan on using only fake corals you will only need to light the tank in a manner in which you can see them. If you plan on keeping seahorse friendly corals, then you will need to get a light to sustain them. I would stay away from metal halides, they are to bright for the animals.
Compatibilty with other species is limited. Seahorses are slow eaters, so if an aggresive fish is included in the tank the seahorse will likely starve. Several goby's make great tank mates as do other non aggresive fish. Shrimps also make great companions, but are not safe around fry. Note if the shrimp will fit in the seahorses mouth it will be a snack.
There are several corals that can be kept with seahorses. You will need to avoid anything with a sting or sweeer tentacles as they can proove deadly. Also corals that need intense lighting will not fair well since you cannot have those lights on a seahorse tank.
Different species require different care requirements. Hippocampus Erectus make great starter horses and are among the easier to breed. Hippocampus Reidi are often called Brazalians are also gorgeous. (If you follow Mellissa's link to the seahorse tank with corals you can see my two reidi in there home.) Some species such as pot bellies will require you to purchase a chiller for your tank.
Breeding seahorses is a topic all of it's own. There are several methods and different species require differnet things. Here is a very fast overview.
Seahorse fry need to be seperated from your main tank and raised in a nursery tank. the water will need to be agitaed to keep them from floating on the top so they do not snick air. Rots, Cocopods, and freshly hatched (with in 4 hours) bbs are the nutrient staple for the first ten days. Then enriched bbs and brine shrimp.Larger foods like cycopleeze and finely chopped frozen mysis can be added, after significant growth. Then larger mysis, until they can eat full mysis. Fry need to be fed 4 to 6 times a day, with uneaten food removed promptly. Growout tanks will be required as the seahorses outgrow the small nursery tank.
Seahorse fry rank up there with clown fish as being extremely diffucult to raise. There are community's such as the Seahorse Breeders Network, who have proven very successful at raising seahorses in the home aquarium.
This is all just a very brief very general overview as to what keeping seahorses will entail. It is by no means the end of your search but hopefully enough of a start to anwser some questions and fill your mind with new questions to answer.
For more direct advice from a forum of people who have been successfully keeping seahorses for years please visit seahorse.org. I feel bad solicting the site on another, but this site is not answering your questions.