If you feel that your stallion is gravid, the best thing to do depends on whether or not you want to attempt to raise the baby seahorses, which is a monumental task that is beyond the capabilities of most home aquarists because of the huge amount of time and resources that are required to successfully raise the young.
If you will contact me off list via e-mail at the following address, Joanna, I can provide you with detailed information and illustrations explaining how to raise newborn seahorses:
After looking through the information, you can then decide for yourself if you think it is feasible or practical for you to attempt rearing the young.
Best of luck with your expectant father in the meantime, Joanna!
Pete Giwojna, Ocean Rider Tech Support