Thanks for the update! It’s great to hear that your seahorse has regained his appetite and is doing so much better now. You did very well to administer the freshwater dip and install the extra airstone’s in your seahorse tank before you had to leave for your trip.
That was an excellent start towards correcting the problem, Sindy, but I would encourage you to follow up and reduce the salinity in your seahorse tank to around 1.015-1.017, as we discussed in my previous post. The fact that your seahorse responded well to the freshwater dip and the extra airstone’s suggests a possible problem with gill parasites, and reducing the salinity in your main tank is a very good way to address such parasites. The freshwater dip would have cleansed the parasites from your seahorse and provided him with some temporary relief, but we also need to control any remaining parasites in the main tank, and hyposalinity often produces excellent results in that regard.
Not only will we lowering the specific gravity help eradicate any gills flukes or protozoan parasites from your main tank, it will also further increase the dissolved oxygen levels in the aquarium, which should also be beneficial in this situation. (The lower the salinity, the more dissolved gases the aquarium water can hold in solution.)
So I would continue to use the additional airstones you installed and drop the specific gravity in your seahorse tank to 1.015-1.017 for a period of 4-6 weeks, Sindy. That is a long enough to eliminate most of the common parasites that attack the gills of fish. If your seahorse is still going strong with no signs of any problems six weeks from now, then you can be fairly certain that the hyposalinity did its job, and that it’s safe to consider adding another seahorse to your tank.
But I would not add any new specimens to the tank before then — you’ll want to be quite sure there isn’t a disease problem in the aquarium and that you have eliminated any gill parasites from the tank before you introduce another seahorse or other new specimens.
Best of luck with your new seahorse tank, Sindy!