why are my discus breathing rapidly

[JJ1]

this is my first post to this forum as usually i can get my answers by just reading the posts but this one has got me puzzled , i did a thirty percent water change 4 days ago and rinsed my cannister filters out in the old water which i have done before with all my other different fish in other tanks with this same trickle filter (i dont know if i had made a mistake as i have been trying to bring down my ph for a while now and read in several books that peat, ro and just boiling the water before you put it in the tank can make it soft ), so i used boiled water that had been allowed to slightly cool down ,everything went fine and yesterday my wife told me they were acting strange by breathing rapidly and going to the top and breathing then swimming back round but all the while they still had rapid gill movement , i have looked in all my discus books but they do not display signs og gill flukes or any parasites i am puzzled as i tested the water and the ph was 6.5 which had lowered and the nitrites had risen slightley above zero i just hope the rinsing of the filter cannisters has not caused undue poor water , as a precaution as in the books we did a 25 to 30 percent water change and today they are still having rapid gill movement but are not shy and have eaten blood worm will test the water again later at the same time of evening but if any body could help with advice i would be most gratefull
thank you
JJ1 :roll:

[Merrilyn]

Did your water testing reveal any level of ammonia ?

What temperature are you running your tank, and do you have an airstone in the tank ?

Was there any improvement in the breathing shortly after the waterchange, or did the rapid gill movements remain the same?

[sponge2]

Have you checked your tds reading and what is your kh levels,
If one has spiked it could cause them to strugle.
Can you get hold of any wormer plus as it mite be worth running a treatment.

[the german]

heavy breathing has nothing to do with conductivity or kh.
like merrilyn said check for amonia

[ILLUSN]

also a sudden incrrease in temp, check your heater, hotter water less disolved O2.

I had fish doing the same after a heater played up in the fish room on the hot saturday sydney just had (temp was 37C!!!!!!!!)