Pipefishes are beautiful yet tricky beasts!
Most NEVER train to frozen & perish if not fed properly!
The best food would be Mysid shrimp that is alive, they are expensive though!!!! Sooooo a nice cheaper alternative would be live brine.
You do need to enrich it as it's nutritional value is rather low, & although you are feeding the pipe, it takes more energy to digest it than it actually recieves from it. A nice slow death! eeekkk!!
Buy some selcon & gut load those bad boys before feeding to your pipe. Also, they love amphipods & those are also really good for them. (Don't know what yoru tank population is) You can also buy them to seed your aquarium, but unless you have a refugium, it will be hard to keep the pod populations where you would need them to sustain your pipe.
I hope this helped in any way & good luck!! =)