Goldfish and Fantail sitting on bottom not feeding - HELP

Szaki wrote:
You have high Nitrite or Ammonia in the tank, from over feeding or some
other reasons. 60% water change don't do it, if it's high. Change the water
completely or few water changes, 3/4, 1/2,1/2, than 1/4 water changes, same
day. Check your water quality at petstore, free, or buy a kit. It's much
better if you learn how.
High Ammonia or Nitrite will kill your fish within a day, also stresses it
out, that's why they get diseases.
Can you picture it, if I lock you in a room, for months, nothing comes out,
only food goes in.
Your waist, breath, CO2 just accumulate in there. Wouldn't you get stressed
out after a while?

Julius

If you say I have high nitrite or ammonia and these will kill my fish
within a day then why have they been sat at the bottom but very much
alive for over a week

The water was completely fresh 3 weeks ago when I moved into my new house