All meds have failed...How about bleaching everything?

[WatermelonsInSe]

My new 90 l (~23 gallon) aquarium that I set up in July has been a horrible disaster. I had some experience with aquariums in the past + I did a lot of research before starting it, so I thought I was well prepared. My fish, Pygmy cories and lambchop rasboras, got sick almost immediately after getting them (main symptoms - itching, paleness, sometimes rapid breathing) and nothing seems to help. I have tried a range of different medicines with barely any improvements in fishes' health - anti-fluke meds (praziquantel), anti-protozoan meds (formalin, malachite green), antibiotics (nifurpirinol) and careful dosing of salt, all with proper treatment schedules. I have tested water conditions at home and multiple times at store (yes, I know about cycling). Nothing has helped. So my big question is - could putting fish in a hospital tank and sterilizing everything help? Like - throwing out old gravel, boiling driftwood, bleaching equipment and tank, sterilizing plants with alum, and starting the cycle all over again? And then perhaps, before putting fishes back, giving them a quick dip of some general meds like copper?

 

[Aiken Drum]

Putting fish in a hospital tank might rule out the cause being something in the tank. Sometimes fish just aren't responsive to treatment, or you havent found the correct treatment.

 

[Aiken Drum]

You've removed any carbon from filters while medicating?

 

[WatermelonsInSe]

Yes, I removed carbon. Also cleaned substrate and filter before treatment and followed instructions regarding light. I hope that a hospital tank will help to reduce their chances of getting reinfected from the environment.