120 Gallon Tank Danio gulping


A few weeks ago one of my giant danios started gulping constantly ( not always at the surface ) I tested the O2 levels and they were medium to high and the ammonia was 0. I moved it to a hospital tank and treated with bacterial and fungul meds but after a few days it died. Now another giant danio is also constantly gulping and not swimming with the others.
I noticed it's gills are constantly open as well so I'm thinking it's obviously struggling to get enough oxygen but I have just tested the O2 levels and they are still high and again all the other fish are good, I also tested all the water parameters and all are good
So the question is what's wrong with the fish's gills? One possibly is Gill flukes and I have ordered some meds. for this that will arrive on tuesday and I have started daily salt baths today.
Can anyone think of anything else that could be affecting the fish in this way?
Any ideas would be gratefully received.


In some fish difficulty breathing can be a symptom of internal problems, like dropsy.

Do you know your nitrite and nitrate? Do you think there are any oils/ contaminants in the tank? Is your water conditioner expired or faulty?
Top Bottom