I'm sorry to hear that. It's worrisome in that you haven't seen any visible signs on the exterior of these seahorses.
Have you already separated the dwarfs?
Maybe you could set up the one gallon you previously mentioned and move the fry into that while adding the adult dwarfs to the hospital container with the erectus. It would mean changing the water in that tank daily, maybe about 20%, along with the 50% water change in the treatment container.
If you do it, don't use anything from the display tank without first sterilizing it as you may be just transferring the problem one tank to another. You won't need much in the way of artificial hitching but again, you will need open ended airline aeration.
This will also give you some time to do a rigorous cleaning of the display tank and put all new water in it. Check after to see if it recycles.
Have you already separated the dwarfs?
Maybe you could set up the one gallon you previously mentioned and move the fry into that while adding the adult dwarfs to the hospital container with the erectus. It would mean changing the water in that tank daily, maybe about 20%, along with the 50% water change in the treatment container.
If you do it, don't use anything from the display tank without first sterilizing it as you may be just transferring the problem one tank to another. You won't need much in the way of artificial hitching but again, you will need open ended airline aeration.
This will also give you some time to do a rigorous cleaning of the display tank and put all new water in it. Check after to see if it recycles.