Hi,
Bryce, I did not see the picture...I don't know how I missed that. At least it's in a cycled tank. LOL...I'm not the seahorse person, I think I'm the only one left that keeps them.
The power head it's hitched to is dangerous, the horse can get it's tail injured, it needs a power head that's more closed up. It's stressed if it's breathing heavy. Adult seahorses can handle current, so unless it's getting blowed around and clinging for dear life, it's probably okay. No heater at all, they can get burned since they hitch to everything, and if it's sick with an infection (a strong possibility) you want to drop the temp to 68 if you can.
The problem with wild caught horses are that they only eat live food. So you need to address that. Is it eating? They like amphipods, copepods are too small, Mysis shrimp if they are small enough.
Tropical seahorses need a colder tank, no higher then 74 degrees, most reef tanks are way too warm for them. You can also go to a site called Seahorse.org, they are seahorse experts, it's all they attend to.