My seahorses are breathing rapid and hasnt eaten in 1.5 days ... please help !!

[The_Paradox]

There are the 4 small cardinal fish , they are new, about 1 week but we're put through a qt , non medicated qt , just observation

Could be stress.

 

[vcarlyle62]

So things have not improved, still breathing fast and one has passed. I did a freshwater dip and maybe could see dust looking things in the water after but really unsure. They still seem to be rapid breathing. Water parameters are the same, no swings. Temp and salinity same, no swings. I am just at a loss what to do next and I'm terrified that anything I do will make it worse. Any seahorse experts able to provide some advice?