Oh boy, that might be a bit of a gamble. Coral banded shrimp (Stenopus hispidus) are well armed and their feisty, pugnacious temperament has earned them the nickname or common name of Boxer Shrimp, which is well justified.
In nature, they may perform a beneficial service by grooming the larger fish such as green morays or overgrown groupers. But in the aquarium, with small reef fishes, they tend to "clean" any small fish they can get their claws on right down to the bone. They have very poor vision and operate mainly by touch, aided by their umbrella of feelers, and their sense of smell, which is very good. They have an unfortunate tendency to try to bear hug just about anything within reach that moves or gives off an intriguing aroma. I would hate to be the seahorse that wandered within hugging distance of one of these coral bandits, and in the confines of the aquarium, that’s something that’s likely to happen, sooner or later…
I don’t think I’d take a chance on the coral banded shrimp, David. I would see if you could trade him in for a genuine cleaner shrimp, which make great companions for seahorses, if they’re large enough. Peppermint Shrimp (Lysmata wurdemanni), Fire Shrimp (Lysmata debelius), and/or Scarlet Cleaner Shrimp or Skunk Cleaner Shrimp (Lysmata amboinensis) would all be better options than Stenopus hispidus, sir.
Peppermint shrimp (Lysmata wurdemanni) are a favorite with seahorse keepers because they eat Aiptasia rock anemones, and both the peppermints and Scarlet cleaner shrimp (Lysmata amboinensis) will perform another useful service by grooming the seahorses and cleaning them of ectoparasites. As an added bonus, they reproduce regularly in the aquarium, producing swarms of larval nauplii that the seahorses love to eat.
Just remember, it is important to select the largest possible cleaner shrimp for your seahorse tank(s). Seahorses will actively hunt small cleaner shrimp and they are quite capable of killing shrimp that are far too big to swallow whole, so the cleaners need to be large enough that they are not regarded as potential prey.
Best of luck preparing for your first seahorses, David!