All Fish Looking Ill!

Hi again everyone.

Disaster is striking. Starting to lose all types of fish in my tank. All are showing signs of ammonia poisoning but I've checked all my levels and all is good. My ammonia has never shown a true yellow just a very slight green tint. I have two test kits and both have always shown the same.
Nitrite 0
Nitrate 30. My nitrate is always a little higher as it that way through my tap. No pH swing that's stable.
This is affecting everything from rams to tetras. They all have slightly red gills and are sucking water in like crazy. The only one that seems nearly OK is the dwarf gourami. Possibly I'm thinking due to his labyrinth gland. Oh and the bristle nose.

Anyone had any similar problems and found any info. Anything will help.

First port of call is to do a very large water change. 80% or more. Report back once that is done. This should always be the first step if nothing else has changes recently.  Have a think and let us know?

Hi @hilly

Could you please let us know which test kit you are using for ammonia, nitrite and nitrate? And, are they within their expiry dates? Also, would you happen to know the water GH, KH and temperature? How did you cycle the tank and was that done recently? That'll do for the moment.

JPC