Sorry for the delay in replying! I can read but cant log in on my phone so this was my first chance! I will answer from the earliest down.
Yes they are in the same tank as the new and old neons (200l - roughly 55gal). I have never seen them like this before and being some of my oldest fish, they have experienced the addition of more or less everything else!
I cant really test during the day, I can morning and evening but thats it. All four are Bronze Cory
. I am waiting for the store to get more in so I can make it up to 6, they haven't had any in a while but are hoping to get some in the next month.
They had a water change Sunday (before new fish) and I tested then and I tested when I noticed the problem yesterday and there is no Ammonia, no Nitrite or Nitrate. Thats why I tested for everything else! I was planning on adding air when I put my new filter in as the new one doesnt pump air, I have a bendy bubble bar but no pump yet - Question, If I get a pump with 2 outlets but only use one outlet for now - will I loose pressure in the outlet I do use? and will the one I dont use make a noise?
Yes they have been in the tank since the beginning (around 9 months) they are Bronze Cory
. I noticed the fast respiration for the first time yesterday evening. They are still at it now and are unusually sluggish almost weak. I'm not here throughout the day so I dont know if they have been the same all day. Ammonia is at 0, Nitrate is 0, Nitrite is at 0.
New fish include 12 Neon Tetra
and 4 Dwarf Neon Rainbowfish
, all added Sunday afternoon.
I added a new filter a week ago (running alongside my old one for now) but I dont think it would be that. No new decor in a long time.
The only thing going in the water is API StressCoat+ and the occasional dose of greenaway (not done for weeks).
I think thats everything, Thank you for all the help! :)