Can you give a little more information about your situation? Sometimes gas bubble disease seems to be caused by maintenance issues, i.e. water to slow, infrequent water changes, tank or filtration too small for waste produced, among others. The wrong kind of skimmer can also cause problems, as well as problematic pumps which cause cavitation of bubbles. If those are the cause, and you correct those problems, it can go away on it's own.
Information that would be useful is details about your setup, as well as water quality (ammonia, nitrite, nitrate, ph, phosphate, temperature, kh, calcium). How long you had the seahorse and where the gas bubble is appearing is also helpful.
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