If anyone has a reef tank with both fish and seahorses can you pm me? I am interested in that possibility for the future, although some articles say it should not be done.
There are very few fishes that can live in harmony with seahorses. Most serious keepers will advise to have a species only tank. I myself love my seahorse tank, but it is more work then my mixed reef tank. It also cost more as I also had to invest in a chiller as the tank naturally got to 76 in my house which is higher then the suggested temp. I do have fish and starfish in my seahorse tank. 3 firefish and a royal gramma. I am trying to catch the royal right now as it has grown to the point where seahorses are competing for food and he is a lot quicker then him.
Find @yveterinarian post on seahorses. After you read that you will either see the challenges you face or you will be ready to face them. Either way it's a good read it caused me to shy away from the idea a few months ago until I get a more stable grasp of the hobby.
As Torx said, you are best to do a species only tank. Seahorses are very slow eaters, and will often only get a bite or two before all the other food has been eaten by the other fish. If you are set on adding a few tank mates, make sure they are peaceful and take their time eating as well. A good choice would be the Catalina goby. They're small, colourful, prefer cooler water, and aren't aggressive eaters.