Hi Matt, I see you're fairly new to the hobby... WELCOME TO OUR ADDICTION!
Since you are new to horses too, let me give you some pointers that will hopefully save you money and heart ache. First, dont ever buy a seahorse based on color - or for that matter with a name like that. There are no "yellow seahorses". If the person or fish store selling you the horses cannot tell you the correct name (i.e. Reidi, Erectus, Comes, etc.), chances are the horses are not captive bred. The problem with horses that are not CB is feeding, since pen/net raised or wild caught horses may not take to frozen food right away or even at all. Then you run into the predicament of having to find live foods for them which is no easy task (and expensive too).
Anyways, to answer your questions... what kind of fish and inverts do you have? I ask because most fish are too aggressive to be housed with SH. Horses are very docile and gentle. They move slow and will be quickly out-competed for food. They can be kept with slow moving fish such as gobies or cardinals, and some firefish, but ideally should be kept alone in a SH dedicated tank. Also, the inverts you keep also need to be seahorse friendly. Take a look at this site/document which gives you an idea of what you can and cannot keep with seahorses:
http://www.seahorse.org/library/art...tankmates.shtml
Some crabs can bother and harrass SH and some will even eat them! (I just found that horrible site in my tank yesterday as I am keeping a friend's livestock while he fixes his tank - he HAD crabs that ate my lovely little girl - emphasis on HAD...lol).
As far as corals go, softies are fine, especially leathers. Try not to keep anything in there with a mouth, such as acans, etc., which can eat the horses, or corals with stinging tentacles such as frogspawn or torch, as these will sting them. Leathers are perfect for SH tanks and in my experience, they are generally not bothered by the horses hitching on them. Another great coral for SH tanks are gorgonias. Not only do they add hitching posts for the ponies, but they provide bright color to the tank and some say it helps horses color up. You can also add lots of colorful macro algaes which look great and gove your tank a more "natural" look. A good supplier of macros is John Maloney at Reef Cleaners (
www.reefcleaners.org). He is very helpful and knowledgeable.
I hope the above helps. If you have any more questions feel free to ask. This is a very friendly and helpful community.
